Hi Group! I'll try to make this short and to the point, so please, bear with me... I have a variety of Mac Pro workstations within my enterprise with multiple user Active Directory logins. A majority of these AD logins also use Parallels as part of their workflow. I was delegated the task of upgrading XP to SP3. Yes, finally! Using the local admin account on the Mac and in Windows, I used Software Update (in Windows) to upgrade the workstations individually (I had some problems in the past using ALTIRIS to push upgrades of this size and nature, so I figured I'd be safe and upgrade them manually). Once finished with the upgrade, I made sure not only to reboot Windows a few times but also shutdown Windows and Parallels and reopen to be sure everything is in working order. I even logged into my AD account just to be sure everything else (authentication wise) was working correctly in Windows. And it was, perfectly. Until... Someone else logs into the Mac, opens Parallels and start Windows, a BSOD occurs. Or some other traumatizing error that I didn't get or see when I was logged in. Sometimes even making Window unrepairable. I've even see problems with the Parallels tools. Where even though it was installed under a different login (Mac and Windows) the environment itself becomes unresponsive. Leading to an uninstall and reinstall of the software. Anyone have any thoughts on this? Does each user require their own virtual HD and/or environment? Thanks!