--- a/toolkit/xre/ProfileReset.cpp
+++ b/toolkit/xre/ProfileReset.cpp
@@ -80,35 +80,56 @@ ProfileResetCleanup(nsIToolkitProfile* a
 
   nsXPIDLString resetBackupDirectoryName;
 
   static const PRUnichar* kResetBackupDirectory = NS_LITERAL_STRING("resetBackupDirectory").get();
   rv = sb->FormatStringFromName(kResetBackupDirectory, params, 2,
                                 getter_Copies(resetBackupDirectoryName));
 
   // Get info to copy the old root profile dir to the desktop as a backup.
-  nsCOMPtr<nsIFile> backupDest, uniqueDest;
+  nsCOMPtr<nsIFile> backupDest, containerDest, profileDest;
   rv = NS_GetSpecialDirectory(NS_OS_DESKTOP_DIR, getter_AddRefs(backupDest));
   if (NS_FAILED(rv)) {
     // Fall back to the home directory if the desktop is not available.
     rv = NS_GetSpecialDirectory(NS_OS_HOME_DIR, getter_AddRefs(backupDest));
     if (NS_FAILED(rv)) return rv;
   }
 
-  // Try to get a unique backup directory name.
-  backupDest->Clone(getter_AddRefs(uniqueDest));
-  uniqueDest->Append(resetBackupDirectoryName);
-  rv = uniqueDest->CreateUnique(nsIFile::DIRECTORY_TYPE, 0700);
+  // Try to create a directory for all the backups
+  backupDest->Clone(getter_AddRefs(containerDest));
+  containerDest->Append(resetBackupDirectoryName);
+  rv = containerDest->Create(nsIFile::DIRECTORY_TYPE, 0700);
+  // It's OK if it already exists, if and only if it is a directory
+  if (rv == NS_ERROR_FILE_ALREADY_EXISTS) {
+    bool containerIsDir;
+    rv = containerDest->IsDirectory(&containerIsDir);
+    if (NS_FAILED(rv) || !containerIsDir) {
+      return rv;
+    }
+  } else if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // Get the name of the profile
+  nsAutoString leafName;
+  rv = profileDir->GetLeafName(leafName);
   if (NS_FAILED(rv)) return rv;
 
-  nsAutoString leafName;
-  rv = uniqueDest->GetLeafName(leafName);
+  // Try to create a unique directory for the profile:
+  containerDest->Clone(getter_AddRefs(profileDest));
+  profileDest->Append(leafName);
+  rv = profileDest->CreateUnique(nsIFile::DIRECTORY_TYPE, 0700);
   if (NS_FAILED(rv)) return rv;
+
+  // Get the unique profile name
+  rv = profileDest->GetLeafName(leafName);
+  if (NS_FAILED(rv)) return rv;
+
   // Delete the empty directory that CreateUnique just created.
-  rv = uniqueDest->Remove(false);
+  rv = profileDest->Remove(false);
   if (NS_FAILED(rv)) return rv;
 
   // Show a progress window while the cleanup happens since the disk I/O can take time.
   nsCOMPtr<nsIWindowWatcher> windowWatcher(do_GetService(NS_WINDOWWATCHER_CONTRACTID));
   if (!windowWatcher) return NS_ERROR_FAILURE;
 
   nsCOMPtr<nsIAppStartup> appStartup(do_GetService(NS_APPSTARTUP_CONTRACTID));
   if (!appStartup) return NS_ERROR_FAILURE;
@@ -123,31 +144,31 @@ ProfileResetCleanup(nsIToolkitProfile* a
   if (NS_FAILED(rv)) return rv;
 
   // Create a new thread to do the bulk of profile cleanup to stay responsive.
   nsCOMPtr<nsIThreadManager> tm = do_GetService(NS_THREADMANAGER_CONTRACTID);
   nsCOMPtr<nsIThread> cleanupThread;
   rv = tm->NewThread(0, 0, getter_AddRefs(cleanupThread));
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIRunnable> runnable = new ProfileResetCleanupAsyncTask(profileDir, profileLocalDir,
-                                                                      backupDest, leafName);
+                                                                      containerDest, leafName);
     cleanupThread->Dispatch(runnable, nsIThread::DISPATCH_NORMAL);
     // The result callback will shut down the worker thread.
 
     nsIThread *thread = NS_GetCurrentThread();
     // Wait for the cleanup thread to complete.
     while(!gProfileResetCleanupCompleted) {
       NS_ProcessNextEvent(thread);
     }
   } else {
     gProfileResetCleanupCompleted = true;
     NS_WARNING("Cleanup thread creation failed");
     return rv;
   }
   // Close the progress window now that the cleanup thread is done.
   progressWindow->Close();
 
-  // Delete the old profile from profiles.ini. The folder was already deleted above.
+  // Delete the old profile from profiles.ini. The folder was already deleted by the thread above.
   rv = aOldProfile->Remove(false);
   if (NS_FAILED(rv)) NS_WARNING("Could not remove the profile");
 
   return rv;
 }

--- a/toolkit/xre/ProfileReset.h
+++ b/toolkit/xre/ProfileReset.h
@@ -33,30 +33,30 @@ public:
 private:
   nsCOMPtr<nsIThread> mWorkerThread;
 };
 
 class ProfileResetCleanupAsyncTask : public nsRunnable
 {
 public:
   ProfileResetCleanupAsyncTask(nsIFile* aProfileDir, nsIFile* aProfileLocalDir,
-                               nsIFile* aDesktop, const nsAString &aLeafName)
+                               nsIFile* aTargetDir, const nsAString &aLeafName)
     : mProfileDir(aProfileDir)
     , mProfileLocalDir(aProfileLocalDir)
-    , mDesktop(aDesktop)
+    , mTargetDir(aTargetDir)
     , mLeafName(aLeafName)
   { }
 
 /**
  * Copy a root profile to a backup folder before deleting it.  Then delete the local profile dir.
  */
   NS_IMETHOD Run()
   {
     // Copy to the destination then delete the profile. A move doesn't follow links.
-    nsresult rv = mProfileDir->CopyToFollowingLinks(mDesktop, mLeafName);
+    nsresult rv = mProfileDir->CopyToFollowingLinks(mTargetDir, mLeafName);
     if (NS_SUCCEEDED(rv))
       rv = mProfileDir->Remove(true);
     else
       NS_WARNING("Could not backup the root profile directory");
 
     // If we have a separate local cache profile directory, just delete it.
     // Don't return an error if this fails so that reset can proceed if it can't be deleted.
     bool sameDir;
@@ -70,11 +70,11 @@ public:
     nsCOMPtr<nsIRunnable> resultRunnable = new ProfileResetCleanupResultTask();
     NS_DispatchToMainThread(resultRunnable);
     return NS_OK;
   }
 
 private:
   nsCOMPtr<nsIFile> mProfileDir;
   nsCOMPtr<nsIFile> mProfileLocalDir;
-  nsCOMPtr<nsIFile> mDesktop;
+  nsCOMPtr<nsIFile> mTargetDir;
   nsAutoString mLeafName;
 };