In one very particular circumstance, my computer hangs while Avast shields are enabled.
Windows XP Fast User Switching is enabled; Avast shields are enabled.
The first user account to log on is an administrator account; then,
The Windows Welcome Screen is accessed (shortcut = Windows Key+L); then,
The second user account to log on is a limited account; then,
The second user attempts to log off while the Avast shields are enabled.
At step 5, the limited user is logged off, but the computer hangs before the Windows Welcome Screen is displayed. No event is logged to Event Viewer or the Dr. Watson error log. The keyboard is frozen; the screen is gray. ALT+CNTL+DEL does not work. The only recovery is a “hard”, power-off shutdown.
If, however, between steps 4 and 5 above, the second, limited user account disables all Avast shields before logging off, the limited user account is logged off normally and the Windows Welcome Screen is displayed properly. No hang.
I experienced a very similar problem; the computer hung when logging off the second, limited user. The only way to get out of the hang was to do a power-switch forced shutdown.
I found that disabling and then re-enabling the Avast shields seemed to cure the problem. I have not found it necessary to disable the shields each time the second (limited) user logs off. It has not happened since.
Windows XP SP3
Avast 7.0.1456 (now - unfortunately cannot remember which version I was on when the problem started)
I spoke too soon, I am still getting the hang when the Limited User account logs off (the Limited Account is rarely used, so the problem diesn’t arise often, but it is still highly annoying, because a hard shutdown seems to be the only way out).
What happens when you log off as admin and then log on as limited and vice versa? (Log off as limited and then log on as admin, only one account running at a time, in effect not using Fast User Switching, (or as when FUS is disabled.)