diff --git a/checkin_notes b/checkin_notes
index d67ff8a35c..f38be3c759 100755
--- a/checkin_notes
+++ b/checkin_notes
@@ -6474,6 +6474,8 @@ Charlie 21 June 2006
         - Installer calls check_security() after creating users and groups  
             and setting owners and permissions for Manager, Client and data; 
             retries up to 5 times if error.
+        - Installer script calls postinstall application twice with different 
+            arguments, waits for first call to complete.
         - Manager and Client report unique error codes from check_security().
 
     client/
@@ -6487,4 +6489,6 @@ Charlie 21 June 2006
         boinc.xcodeproj/
             project.pbxproj
     mac_installer/
+        postinstall
+        postupgrade
         Postinstall.cpp
diff --git a/mac_build/English.lproj/InfoPlist.strings b/mac_build/English.lproj/InfoPlist.strings
index 7d63ca852f..b8a3d176be 100755
--- a/mac_build/English.lproj/InfoPlist.strings
+++ b/mac_build/English.lproj/InfoPlist.strings
@@ -1,5 +1,5 @@
 /* Localized versions of Info.plist keys */
 
 CFBundleName = "BOINC";
-CFBundleShortVersionString = "BOINC version 5.5.2";
-CFBundleGetInfoString = "BOINC version 5.5.2, Copyright 2006 University of California.";
+CFBundleShortVersionString = "BOINC version 5.5.3";
+CFBundleGetInfoString = "BOINC version 5.5.3, Copyright 2006 University of California.";
diff --git a/mac_build/Info.plist b/mac_build/Info.plist
index 7155627e5b..45bfaa5d7b 100644
--- a/mac_build/Info.plist
+++ b/mac_build/Info.plist
@@ -17,6 +17,6 @@
 	<key>CFBundleSignature</key>
 	<string>BNC!</string>
 	<key>CFBundleVersion</key>
-	<string>5.5.2</string>
+	<string>5.5.3</string>
 </dict>
 </plist>
diff --git a/mac_build/Installer-Info.plist b/mac_build/Installer-Info.plist
index 1e948a818f..ef2445bab2 100644
--- a/mac_build/Installer-Info.plist
+++ b/mac_build/Installer-Info.plist
@@ -15,6 +15,6 @@
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>5.5.2</string>
+	<string>5.5.3</string>
 </dict>
 </plist>
diff --git a/mac_build/ScreenSaver-Info.plist b/mac_build/ScreenSaver-Info.plist
index ec2eaff0f1..41f28311b1 100644
--- a/mac_build/ScreenSaver-Info.plist
+++ b/mac_build/ScreenSaver-Info.plist
@@ -17,7 +17,7 @@
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>5.5.2</string>
+	<string>5.5.3</string>
 	<key>NSPrincipalClass</key>
 	<string>BOINC_Saver_ModuleView</string>
 </dict>
diff --git a/mac_build/SystemMenu-Info.plist b/mac_build/SystemMenu-Info.plist
index 3b2c7d5630..393e6881dd 100644
--- a/mac_build/SystemMenu-Info.plist
+++ b/mac_build/SystemMenu-Info.plist
@@ -15,6 +15,6 @@
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>5.5.2</string>
+	<string>5.5.3</string>
 </dict>
 </plist>
diff --git a/mac_installer/PostInstall.cpp b/mac_installer/PostInstall.cpp
index ad83084b11..16b6ddf0a9 100755
--- a/mac_installer/PostInstall.cpp
+++ b/mac_installer/PostInstall.cpp
@@ -35,6 +35,7 @@
 #include "SetupSecurity.h"
 
 void Initialize(void);	/* function prototypes */
+int LaunchBoinc(void);
 void SetLoginItem(long brandID);
 void SetUIDBackToUser (void);
 OSErr UpdateAllVisibleUsers(long brandID);
@@ -69,6 +70,11 @@ int main(int argc, char *argv[])
     char                    s[256];
 #endif
     
+    for (i=0; i<argc; i++) {
+        if (strcmp(argv[i], "-part2") == 0) {
+            return LaunchBoinc();
+        }
+    }
     Initialize();
 
     ::GetCurrentProcess (&ourProcess);
@@ -130,28 +136,32 @@ int main(int argc, char *argv[])
 
     for (i=0; i<5; ++i) {
         err = CreateBOINCUsersAndGroups();
+        if (err != noErr) {
 print_to_log_file("CreateBOINCUsersAndGroups returned %d (=%d)", err, i);
-        if (err != noErr)
             continue;
+        }
         
        if (brandID == 1)
             err = SetBOINCAppOwnersGroupsAndPermissions(p);
         else
             err = SetBOINCAppOwnersGroupsAndPermissions(p);
         
+        if (err != noErr) {
 print_to_log_file("SetBOINCAppOwnersGroupsAndPermissions returned %d (=%d)", err, i);
-        if (err != noErr)
             continue;
+        }
 
         err = SetBOINCDataOwnersGroupsAndPermissions();
+        if (err != noErr) {
 print_to_log_file("SetBOINCDataOwnersGroupsAndPermissions returned %d (=%d)", err, i);
-        if (err != noErr)
             continue;
+        }
         
         err = check_security(p, "/Library/Application Support/BOINC Data");
+        if (err != noErr) {
 print_to_log_file("check_security returned %d (=%d)", err, i);
-        if (err == noErr)
-            break;
+            continue;
+        }
     }
     
 #else   // ! defined(SANDBOX)
@@ -242,23 +252,49 @@ print_to_log_file("check_security returned %d (=%d)", err, i);
     SetUIDBackToUser ();
     SetLoginItem(brandID);
 #endif
+ 
+    return 0;
+}
 
-    // Launch BOINC Manager when user closes installer or after 15 seconds
+
+int LaunchBoinc()
+{
+    ProcessSerialNumber     installerPSN;
+    long                    brandID = 0;
+    int                     i;
+    pid_t                   installerPID = 0;
+    FSRef                   fileRef;
+    OSStatus                err, err_fsref;
+
+    Initialize();
+
+    err = FindProcess ('APPL', 'xins', &installerPSN);
+    if (err == noErr)
+        err = GetProcessPID(&installerPSN , &installerPID);
+
+
+   // Launch BOINC Manager when user closes installer or after 15 seconds
 
     for (i=0; i<15; i++) { // Wait 15 seconds max for installer to quit
         sleep (1);
-        if (FindProcessPID(NULL, installerPID) == 0)
-            break;
+        if (err == noErr)
+            if (FindProcessPID(NULL, installerPID) == 0)
+                break;
     }
 
-    if (err_fsref == noErr)
-        err = LSOpenFSRef(&fileRef, NULL);
+    brandID = GetBrandID();
 
     // Remove installer package receipt so we can run installer again if needed to fix permissions
-   if (brandID == 1)
+   if (brandID == 1) {
         system ("rm -rf /Library/Receipts/GridRepublic.pkg");
-    else
+        err_fsref = FSPathMakeRef((StringPtr)"/Applications/GridRepublic Desktop.app", &fileRef, NULL);
+    } else {
         system ("rm -rf /Library/Receipts/BOINC.pkg");
+        err_fsref = FSPathMakeRef((StringPtr)"/Applications/BOINCManager.app", &fileRef, NULL);
+    }
+    
+    if (err_fsref == noErr)
+        err = LSOpenFSRef(&fileRef, NULL);
 
     return 0;
 }
diff --git a/mac_installer/postinstall b/mac_installer/postinstall
index 14e73d1635..55bfe6ca94 100644
--- a/mac_installer/postinstall
+++ b/mac_installer/postinstall
@@ -6,6 +6,8 @@
 
 cd "$1"
 # Run the Postinstall Application
-Contents/Resources/PostInstall.app/Contents/MacOS/PostInstall &
+Contents/Resources/PostInstall.app/Contents/MacOS/PostInstall -part1
+
+Contents/Resources/PostInstall.app/Contents/MacOS/PostInstall -part2 &
 
 exit 0
diff --git a/mac_installer/postupgrade b/mac_installer/postupgrade
index 6ac0688f99..73838410b7 100755
--- a/mac_installer/postupgrade
+++ b/mac_installer/postupgrade
@@ -6,6 +6,8 @@
 
 cd "$1"
 # Run the Postinstall Application
-Contents/Resources/PostInstall.app/Contents/MacOS/PostInstall &
+Contents/Resources/PostInstall.app/Contents/MacOS/PostInstall -part1
+
+Contents/Resources/PostInstall.app/Contents/MacOS/PostInstall -part2 &
 
 exit 0