I was in the process of upgrading the XenTools on a XenServer based guest, which is running Exchange 2007 on Windows 2008 (no r2).
It hung, so I rebooted it. Now when I bring it up I get a couple seconds of the Windows progress bar, and then it BSODs with 0x00000007b. This indicates to me that it's choking on whatever storage drivers were bring installed.
Any ideas on how to resolve this? This is a production machine. I've tried doing the StartRep.exe command from the Windows CD, but it couldn't fix the problem. Ran a CHKDSK with no switches.