I have windows XP-SP2 and the latest version of Avast4.
I have two users on my computer. When I work on one session everything works fine. But when I want to change session, the blue icon doesnot appear in the new session and the computer freezes.
When I shut down and restart, everything is OK until I try to change session.
Did you install avast and enter the registration key using ‘The Administrator’ account, not an account with admin privileges ?
This way avast should be available to all users on the system.
If not it may be best to uninstall avast using the account you set it up with, reboot, logon as the administrator and reinstall avast and enter the registration key.