diff --git a/api/boinc_api.cpp b/api/boinc_api.cpp
index 87bca9f2d5..2fe27dfb4c 100644
--- a/api/boinc_api.cpp
+++ b/api/boinc_api.cpp
@@ -860,10 +860,10 @@ int boinc_wu_cpu_time(double& cpu_t) {
 
 int suspend_activities() {
 #ifdef _WIN32
-    static DWORD pid;
-    if (!pid) pid = GetCurrentProcessId();
+    static vector<int> pids;
     if (options.multi_thread) {
-        suspend_or_resume_threads(pid, timer_thread_id, false);
+        if (pids.size() == 0) pids.push_back(GetCurrentProcessId());
+        suspend_or_resume_threads(pids, timer_thread_id, false, true);
     } else {
         SuspendThread(worker_thread_handle);
     }
@@ -872,7 +872,7 @@ int suspend_activities() {
     // suspension is done by signal handler in worker thread
     //
     if (options.multi_process) {
-        suspend_or_resume_descendants(0, false);
+        suspend_or_resume_descendants(false);
     }
 #endif
     return 0;
@@ -880,16 +880,16 @@ int suspend_activities() {
 
 int resume_activities() {
 #ifdef _WIN32
-    static DWORD pid;
-    if (!pid) pid = GetCurrentProcessId();
+    static vector<int> pids;
     if (options.multi_thread) {
-        suspend_or_resume_threads(pid, timer_thread_id, true);
+        if (pids.size() == 0) pids.push_back(GetCurrentProcessId());
+        suspend_or_resume_threads(pids, timer_thread_id, true, true);
     } else {
         ResumeThread(worker_thread_handle);
     }
 #else
     if (options.multi_process) {
-        suspend_or_resume_descendants(0, true);
+        suspend_or_resume_descendants(true);
     }
 #endif
     return 0;
diff --git a/client/gpu_detect.cpp b/client/gpu_detect.cpp
index a4879b98cb..4dce23dd3b 100644
--- a/client/gpu_detect.cpp
+++ b/client/gpu_detect.cpp
@@ -47,13 +47,6 @@
 using std::string;
 using std::vector;
 
-bool in_vector(int n, vector<int>& v) {
-    for (unsigned int i=0; i<v.size(); i++) {
-        if (v[i] == n) return true;
-    }
-    return false;
-}
-
 #ifndef _WIN32
 jmp_buf resume;
 
diff --git a/lib/proc_control.cpp b/lib/proc_control.cpp
index 83ca3d2c43..08715f1271 100644
--- a/lib/proc_control.cpp
+++ b/lib/proc_control.cpp
@@ -40,11 +40,15 @@
 #endif
 
 #include "procinfo.h"
+#include "str_util.h"
+#include "util.h"
 
 #include "proc_control.h"
 
 using std::vector;
 
+//#define DEBUG
+
 static void get_descendants_aux(PROC_MAP& pm, int pid, vector<int>& pids) {
     PROC_MAP::iterator i = pm.find(pid);
     if (i == pm.end()) return;
@@ -67,64 +71,81 @@ void get_descendants(int pid, vector<int>& pids) {
     retval = procinfo_setup(pm);
     if (retval) return;
     get_descendants_aux(pm, pid, pids);
+#ifdef DEBUG
+    fprintf(stderr, "descendants of %d:\n", pid);
+    for (unsigned int i=0; i<pids.size(); i++) {
+        fprintf(stderr, "   %d\n", pids[i]);
+    }
+#endif
 }
 
 #ifdef _WIN32
-// signature of OpenThread()
-//
-typedef HANDLE (WINAPI *tOT)(
-    DWORD dwDesiredAccess, BOOL bInheritHandle, DWORD dwThreadId
-);
 
-// Suspend or resume the threads in a given process,
+// Suspend or resume the threads in a set of processes,
 // but don't suspend 'calling_thread'.
 //
 // The only way to do this on Windows is to enumerate
 // all the threads in the entire system,
-// and find those belonging to the process (ugh!!)
+// and find those belonging to one of the process (ugh!!)
 //
 
 int suspend_or_resume_threads(
-    DWORD pid, DWORD calling_thread_id, bool resume
+    vector<int>pids, DWORD calling_thread_id, bool resume, bool check_exempt
 ) { 
     HANDLE threads, thread;
-    static HMODULE hKernel32Lib = NULL;
     THREADENTRY32 te = {0}; 
-    static tOT pOT = NULL;
- 
-    // Dynamically link to the proper function pointers.
-    if (!hKernel32Lib) {
-        hKernel32Lib = GetModuleHandleA("kernel32.dll");
-    }
-    if (!pOT) {
-        pOT = (tOT) GetProcAddress( hKernel32Lib, "OpenThread" );
-    }
 
-    if (!pOT) {
-        return -1;
+#ifdef DEBUG
+    fprintf(stderr, "start: check_exempt %d %s\n", check_exempt, precision_time_to_string(dtime()));
+    fprintf(stderr, "%s processes", resume?"resume":"suspend");
+    for (unsigned int i=0; i<pids.size(); i++) {
+        fprintf(stderr, " %d", pids[i]);
     }
+    fprintf(stderr, "\n");
+#endif
 
     threads = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0); 
-    if (threads == INVALID_HANDLE_VALUE) return -1;
+    if (threads == INVALID_HANDLE_VALUE) {
+        fprintf(stderr, "CreateToolhelp32Snapshot failed\n");
+        return -1;
+    }
  
     te.dwSize = sizeof(THREADENTRY32); 
     if (!Thread32First(threads, &te)) { 
+        fprintf(stderr, "Thread32First failed\n");
         CloseHandle(threads); 
         return -1;
     }
 
     do { 
-        if (!diagnostics_is_thread_exempt_suspend(te.th32ThreadID)) continue;
+        if (check_exempt && !diagnostics_is_thread_exempt_suspend(te.th32ThreadID)) {
+#ifdef DEBUG
+            fprintf(stderr, "thread is exempt\n");
+#endif
+            continue;
+        }
+        //fprintf(stderr, "thread %d PID %d %s\n", te.th32ThreadID, te.th32OwnerProcessID, precision_time_to_string(dtime()));
         if (te.th32ThreadID == calling_thread_id) continue;
-        if (te.th32OwnerProcessID == pid) {
-            thread = pOT(THREAD_SUSPEND_RESUME, FALSE, te.th32ThreadID);
-            resume ?  ResumeThread(thread) : SuspendThread(thread);
-            CloseHandle(thread);
-        } 
+        if (!in_vector(te.th32OwnerProcessID, pids)) continue;
+        thread = OpenThread(THREAD_SUSPEND_RESUME, FALSE, te.th32ThreadID);
+        if (resume) {
+            DWORD n = ResumeThread(thread);
+#ifdef DEBUG
+            fprintf(stderr, "ResumeThread returns %d\n", n);
+#endif
+        } else {
+            DWORD n = SuspendThread(thread);
+#ifdef DEBUG
+            fprintf(stderr, "SuspendThread returns %d\n", n);
+#endif
+        }
+        CloseHandle(thread);
     } while (Thread32Next(threads, &te)); 
 
     CloseHandle (threads); 
-
+#ifdef DEBUG
+    fprintf(stderr, "end: %s\n", precision_time_to_string(dtime()));
+#endif
     return 0;
 } 
 
@@ -192,39 +213,32 @@ void kill_descendants(int child_pid) {
 }
 #endif
 
-void suspend_or_resume_all(vector<int>& pids, bool resume) {
-    for (unsigned int i=0; i<pids.size(); i++) {
-#ifdef _WIN32
-        suspend_or_resume_threads(pids[i], 0, resume);
-#else
-        kill(pids[i], resume?SIGCONT:SIGSTOP);
-#endif
-    }
-}
-
-
-
-// suspend/resume the descendants of the given process
+// suspend/resume the descendants of the calling process
 // (or if pid==0, the calling process)
 //
-void suspend_or_resume_descendants(int pid, bool resume) {
+void suspend_or_resume_descendants(bool resume) {
     vector<int> descendants;
-    if (!pid) {
 #ifdef _WIN32
-        pid = GetCurrentProcessId();
-#else
-        pid = getpid();
-#endif
-    }
+    int pid = GetCurrentProcessId();
     get_descendants(pid, descendants);
-    suspend_or_resume_all(descendants, resume);
+    suspend_or_resume_threads(descendants, 0, resume, false);
+#else
+    int pid = getpid();
+    get_descendants(pid, descendants);
+    for (unsigned int i=0; i<descendants.size(); i++) {
+        kill(descendants[i], resume?SIGCONT:SIGSTOP);
+    }
+#endif
 }
 
+// used by the wrapper
+//
 void suspend_or_resume_process(int pid, bool resume) {
 #ifdef _WIN32
-    suspend_or_resume_threads(pid, 0, resume);
+    vector<int> pids;
+    pids.push_back(pid);
+    suspend_or_resume_threads(pids, 0, resume, false);
 #else
     ::kill(pid, resume?SIGCONT:SIGSTOP);
 #endif
-
 }
diff --git a/lib/proc_control.h b/lib/proc_control.h
index c8a6df1c47..7dd84308c0 100644
--- a/lib/proc_control.h
+++ b/lib/proc_control.h
@@ -28,11 +28,13 @@ extern bool any_process_exists(std::vector<int>& pids);
 extern void kill_all(std::vector<int>& pids);
 #ifdef _WIN32
 extern void kill_descendants();
-extern int suspend_or_resume_threads(DWORD pid, DWORD threadid, bool resume);
+extern int suspend_or_resume_threads(
+    std::vector<int> pids, DWORD threadid, bool resume, bool check_exempt
+);
 #else
 extern void kill_descendants(int child_pid=0);
 #endif
-extern void suspend_or_resume_descendants(int pid, bool resume);
+extern void suspend_or_resume_descendants(bool resume);
 extern void suspend_or_resume_process(int pid, bool resume);
 
 #endif
diff --git a/lib/procinfo.cpp b/lib/procinfo.cpp
index ff1e9a02f7..3da3cc8844 100644
--- a/lib/procinfo.cpp
+++ b/lib/procinfo.cpp
@@ -31,6 +31,8 @@
 #include <signal.h>
 #endif
 
+#include "util.h"
+
 #include "procinfo.h"
 
 using std::vector;
@@ -64,13 +66,6 @@ void add_child_totals(PROCINFO& pi, PROC_MAP& pm, PROC_MAP::iterator i) {
     }
 }
 
-static inline bool in_vector(int n, vector<int>& v) {
-    for (unsigned int i=0; i<v.size(); i++) {
-        if (n == v[i]) return true;
-    }
-    return false;
-}
-
 // Fill in the given PROCINFO (initially zero except for id)
 // with totals from that process and all its descendants.
 // Set PROCINFO.is_boinc_app for all of them.
diff --git a/lib/util.h b/lib/util.h
index 24dca3c443..b84c140cdd 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -61,6 +61,13 @@ extern void update_average(double, double, double, double, double&, double&);
 
 extern int boinc_calling_thread_cpu_time(double&);
 
+inline bool in_vector(int n, std::vector<int>& v) {
+    for (unsigned int i=0; i<v.size(); i++) {
+        if (n == v[i]) return true;
+    }
+    return false;
+}
+
 // fake a crash
 //
 extern void boinc_crash();
diff --git a/samples/wrapper/wrapper.cpp b/samples/wrapper/wrapper.cpp
index 85fe39b2cc..fc4e77983c 100644
--- a/samples/wrapper/wrapper.cpp
+++ b/samples/wrapper/wrapper.cpp
@@ -66,6 +66,12 @@
 
 #include "regexp.h"
 
+inline void debug_msg(const char* x) {
+#if 0
+    fprintf(stderr, "%s\n", x);
+#endif
+}
+
 #define JOB_FILENAME "job.xml"
 #define CHECKPOINT_FILENAME "wrapper_checkpoint.txt"
 
@@ -792,7 +798,7 @@ void TASK::kill() {
 
 void TASK::stop() {
     if (multi_process) {
-        suspend_or_resume_descendants(0, false);
+        suspend_or_resume_descendants(false);
     } else {
         suspend_or_resume_process(pid, false);
     }
@@ -801,7 +807,7 @@ void TASK::stop() {
 
 void TASK::resume() {
     if (multi_process) {
-        suspend_or_resume_descendants(0, true);
+        suspend_or_resume_descendants(true);
     } else {
         suspend_or_resume_process(pid, true);
     }
@@ -820,24 +826,30 @@ double TASK::cpu_time() {
 void poll_boinc_messages(TASK& task) {
     BOINC_STATUS status;
     boinc_get_status(&status);
+    //fprintf(stderr, "wrapper: polling\n");
     if (status.no_heartbeat) {
+        debug_msg("wrapper: kill");
         task.kill();
         exit(0);
     }
     if (status.quit_request) {
+        debug_msg("wrapper: quit");
         task.kill();
         exit(0);
     }
     if (status.abort_request) {
+        debug_msg("wrapper: abort");
         task.kill();
         exit(0);
     }
     if (status.suspended) {
         if (!task.suspended) {
+            debug_msg("wrapper: suspend");
             task.stop();
         }
     } else {
         if (task.suspended) {
+            debug_msg("wrapper: resume");
             task.resume();
         }
     }
@@ -880,6 +892,10 @@ int main(int argc, char** argv) {
     double checkpoint_cpu_time;
         // total CPU time at last checkpoint
 
+#ifdef _WIN32
+    SetPriorityClass(GetCurrentProcess(), NORMAL_PRIORITY_CLASS);
+#endif
+
     for (int j=1; j<argc; j++) {
         if (!strcmp(argv[j], "--nthreads")) {
             nthreads = atoi(argv[++j]);