Several users have reported a problem in which Windows 7 freezes when waking from sleep/hibernation (usually after the computer has been left alone for some time, the display/monitor turns off, then the user tries to activate the system).
This problem can sometimes be solved by turning off the auto-hide function of the taskbar. To do this, right-click on the Start button then select “Properties.”
Click the taskbar tab, then uncheck the “Auto-hide the taskbar” box. Restart your computer and check for persistence of the issue.