diff --git a/checkin_notes b/checkin_notes
index 7bd1734eda..ce02ba2d5f 100755
--- a/checkin_notes
+++ b/checkin_notes
@@ -7958,6 +7958,7 @@ Charlie 24 July 2006
         macsnoozebadge.xpm (Added)
         macdisconnectbadge.xpm (Added)
 
+
 Rom    25 July 2006
     - Bug Fix: Mac compiler handles std::string a little differently than Windows.
     
@@ -7987,3 +7988,25 @@ Charlie 25 July 2006
         sandbox.php
     mac_installer/
         Postinstall.cpp
+
+David  25 July 2006
+	core client fixes:
+	- fix bug where interrupted downloads failed with checksum error.
+		This was because we were comparing the HTTP status with 200.
+		But partial transfer success is 206.
+		(bug was introduced in June 28 checkin)
+	- on startup, make sure that all files that are
+		supposed to be present actually are.
+		Otherwise set status to NOT_PRESENT,
+		so that they'll be downloaded again.
+	- on reset, clear project_files and user_files vectors
+	- project files: parse and save md5 checksum.
+		Note: this is a placeholder;
+		I'll change it to full FILE_INFO later.
+
+	client/
+		client_state.C,h
+		client_types.C
+		cs_files.C
+		file_xfer.C
+		http_curl.C
diff --git a/client/client_state.C b/client/client_state.C
index da4d450aae..c199c14a5e 100644
--- a/client/client_state.C
+++ b/client/client_state.C
@@ -321,6 +321,8 @@ int CLIENT_STATE::init() {
 #endif
 #endif
 
+    check_file_existence();
+
     return 0;
 }
 
@@ -1232,6 +1234,9 @@ int CLIENT_STATE::reset_project(PROJECT* project) {
         }
     }
 
+    project->user_files.clear();
+    project->project_files.clear();
+
     garbage_collect_always();
 
     // forcibly remove apps and app_versions
diff --git a/client/client_state.h b/client/client_state.h
index 29d07e1aca..7608a0d720 100644
--- a/client/client_state.h
+++ b/client/client_state.h
@@ -337,6 +337,7 @@ public:
 
 // --------------- cs_files.C:
 public:
+    void check_file_existence();
     bool start_new_file_xfer(PERS_FILE_XFER&);
 private:
     int make_project_dirs();
diff --git a/client/client_types.C b/client/client_types.C
index cffe2f909d..748b5a3404 100644
--- a/client/client_types.C
+++ b/client/client_types.C
@@ -499,12 +499,13 @@ int PROJECT::parse_project_file(FILE* in) {
         if (parse_str(buf, "<url>", url, sizeof(url))) {
             finfo.urls.push_back(url);
         }
+        if (parse_str(buf, "<md5_cksum>", finfo.md5_cksum, sizeof(finfo.md5_cksum))) continue;
     }
     return ERR_XML_PARSE;
 }
 
 void PROJECT::write_project_files(MIOFILE& f) {
-    unsigned int i;
+    unsigned int i, j;
 
     if (!project_files.size()) return;
     f.printf("<project_files>\n");
@@ -514,11 +515,25 @@ void PROJECT::write_project_files(MIOFILE& f) {
         f.printf(
             "   <file>\n"
             "      <name>%s</name>\n"
-            "      <open_name>%s</open_name>\n"
-            "   </file>\n",
+            "      <open_name>%s</open_name>\n",
             fip->name,
             fref.open_name
         );
+        if (strlen(fip->md5_cksum)) {
+            f.printf(
+                "      <md5_cksum>%s</md5_cksum>\n",
+                fip->md5_cksum
+            );
+        }
+        for (j=0; j<fip->urls.size(); j++) {
+            f.printf(
+                "      <url>%s</url>\n",
+                fip->urls[j].c_str()
+            );
+        }
+        f.printf(
+            "   </file>\n"
+        );
     }
     f.printf("</project_files>\n");
 }
@@ -976,6 +991,8 @@ int FILE_INFO::merge_info(FILE_INFO& new_info) {
     //
     strcpy(file_signature, new_info.file_signature);
 
+    strcpy(md5_cksum, new_info.md5_cksum);
+
     return 0;
 }
 
diff --git a/client/cs_files.C b/client/cs_files.C
index f8f17d8a30..cb3af5e572 100644
--- a/client/cs_files.C
+++ b/client/cs_files.C
@@ -294,5 +294,25 @@ bool CLIENT_STATE::handle_pers_file_xfers() {
     return action;
 }
 
+// called at startup to ensure that if the core client
+// thinks a file is there, it's actually there
+//
+void CLIENT_STATE::check_file_existence() {
+    unsigned int i;
+    char path[1024];
+
+    for (i=0; i<file_infos.size(); i++) {
+        FILE_INFO* fip = file_infos[i];
+        if (fip->status == FILE_PRESENT) {
+            get_pathname(fip, path);
+            if (!boinc_file_exists(path)) {
+                fip->status = FILE_NOT_PRESENT;
+                msg_printf(NULL, MSG_INFO,
+                    "file %s not found", path
+                );
+            }
+        }
+    }
+}
 
 const char *BOINC_RCSID_66410b3cab = "$Id$";
diff --git a/client/file_xfer.C b/client/file_xfer.C
index 9edd6d64d1..85a8229e94 100644
--- a/client/file_xfer.C
+++ b/client/file_xfer.C
@@ -272,7 +272,7 @@ bool FILE_XFER_SET::poll() {
         // deal with various error cases for downloads
         //
         if (!fxp->is_upload) {
-            if (fxp->response == HTTP_STATUS_OK) {
+            if (fxp->http_op_retval == 0) {
                 // If no HTTP error,
                 // see if we read less than 5 KB and file is incomplete.
                 // If so truncate the amount read,
diff --git a/client/http_curl.C b/client/http_curl.C
index 47ebba4f28..371c2a214a 100644
--- a/client/http_curl.C
+++ b/client/http_curl.C
@@ -571,10 +571,12 @@ size_t libcurl_write(void *ptr, size_t size, size_t nmemb, HTTP_OP* phop) {
     // take the stream param as a FILE* and write to disk
     //CMC TODO: maybe assert stRead == size*nmemb, add exception handling on phop members
     size_t stWrite = fwrite(ptr, size, nmemb, (FILE*) phop->fileOut);
+#if 0
+    if (log_flags.http_debug) {
+        msg_printf(NULL, MSG_INFO, "HTTP: wrote %d bytes", stWrite);
+    }
+#endif
     phop->bytes_xferred += (double)(stWrite);
-    //if (phop->bytes_xferred == (int) phop->content_length)
-    //{ // that's all we need!
-    //}
     phop->update_speed();  // this should update the transfer speed
     return stWrite;
 }