blank welcome screen after waking up from sleep

[i486dx266]

We have about 500 laptops with win 7 pro x64. We have had a few complaints that on occation, after a computer wakes up from sleep mode, the user sees the welcome screen, but no text or logon box - i.e. they can't se any text or textboxes, only the background image of the welcome screen. The only way to end this state is to poweroff/reset the machine. Any ideas?

 

[JMH]

Just a few scattered ideas...

* Has there ever been a BSOD?

* Have you checked in Event Viewer?
Type eventvwr in search.
Go to the Windows Logs > Application / System > in the left hand column.
Note anything in red that relates to the problem experienced.
Please record the event ID, and the Source Code and tell us what they are.

* Consider using Hibernation instead of Sleep

* SFC.
http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html

* Disk check
http://www.sevenforums.com/tutorials/433-disk-check.html