Attempt 2 at landing this....

chrome/browser/renderer_host/browser_render_process_host.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "chrome/browser/renderer_host/browser_render_process_host.h"
 
 #include "build/build_config.h"
@@ skipping 815 matching lines @@
 }
 
 void BrowserRenderProcessHost::OnUpdatedCacheStats(
     const CacheManager::UsageStats& stats) {
   CacheManagerHost::GetInstance()->ObserveStats(host_id(), stats);
 }
 
 void BrowserRenderProcessHost::SetBackgrounded(bool backgrounded) {
   // If the process_ is NULL, the process hasn't been created yet.
   if (process_.handle()) {
-    bool rv = process_.SetProcessBackgrounded(backgrounded);
-    if (!rv) {
-      return;
+    bool should_set_backgrounded = true;
+
+#if defined(OS_WIN)
+    // The cbstext.dll loads as a global GetMessage hook in the browser process
+    // and intercepts/unintercepts the kernel32 API SetPriorityClass in a
+    // background thread. If the UI thread invokes this API just when it is
+    // intercepted the stack is messed up on return from the interceptor
+    // which causes random crashes in the browser process. Our hack for now
+    // is to not invoke the SetPriorityClass API if the dll is loaded.
+    should_set_backgrounded = (GetModuleHandle(L"cbstext.dll") == NULL);
+#endif // OS_WIN
+
+    if (should_set_backgrounded) {
+      bool rv = process_.SetProcessBackgrounded(backgrounded);
+      if (!rv) {
+        return;
+      }
     }
 
     // Now tune the memory footprint of the renderer.
     // If the OS needs to page, we'd rather it page idle renderers.
     BrowserProcess::MemoryModel model = g_browser_process->memory_model();
     if (model < BrowserProcess::HIGH_MEMORY_MODEL) {
       if (backgrounded) {
         if (model == BrowserProcess::LOW_MEMORY_MODEL)
           process_.EmptyWorkingSet();
         else if (model == BrowserProcess::MEDIUM_MEMORY_MODEL)
@@ skipping 34 matching lines @@
         SendUserScriptsUpdate(shared_memory);
       }
       break;
     }
     default: {
       NOTREACHED();
       break;
     }
   }
 }