Hi! I have Windows Vista and just installed avast! this afternoon. I then installed some Windows security updates and had to reboot. I got to the logon screen and entered my password okay, but immediately after my screen went completely black, with the exception of my cursor. After about a minute, my desktop appeared. I then went to the support site, which indicated I should try a diagnostic startup. I did that and had no problems when I logged in again. Are there any steps I can take to determine the cause or do I need to uninstall the program? Thank you!