Some observations:
* Happens almost every time I put the MacBook to sleep
* Logging out of Windows does not fix the problem
* Restarting Windows does fix the problem
* You do not need to restart Parallels, just Windows
* Freezing/unfreezing the Windows image does not affect the problem
Based on this, I would venture to guess that this is a problem with a low-level Parallels Tools service running on Windows. Is there any kind of service that continues running when all users are logged out? The problem most likely resides in that service. It somehow loses is connection to the Mac host, especially when the Mac is put to sleep.
One possible tactic toward a solution is to implement a 'heart beat' carrier in the Parallels Tools service. If the Mac Parallels host detects a loss in heart beat, it could present the user with an Alert box. That would quite reliably pinpoint the events leading up to this bug.
Last edited: Jul 26, 2008