My Vista locked up upon installing the new Parallels, so this was the first place i checked. I see that a few of you are having the same problem as me. I have my copy working now, it was very simple to fix, and I will outline it here. I just completed it, but i have restarted a few times with no issues and all drivers seem to be in working order. This does assume you installed Tools and THEN it started freezing Parallels Desktop Build 3106 or 3036 (tested both) WINDOWS VISTA ULTIMATE RC2 Build 5744 1. Boot into Safe Mode 2. System Restore back to right before you installed parallels tools (Windows will suggest this) 3. Reboot after system restore 4. Make sure Windows Vista boots normally, and no files are missing/corrupt 5. Boot back into Safe Mode 6. Control Panel/Programs and Features 7. Now tell Parallels to install tools (NOTE: The install will NOT POP UP because Safe Mode disables AutoRun) 8. Select Parallels Tools. Press Uninstall/Change 9. Install Parallels Tools as normal 10. Reboot into Windows Vista!