Same problem here. Avast wanted to update the program and I did so. After reboot, the desktop never would show. Hung on the Welcome screen. Went into safe mode and uninstalled Avast and all worked fine. Went to Avast site and downloaded latest Pro version and installed. It booted to desktop but the PC was slow, especially on the Internet. Windows Firewall could not start either. I'm leaving uninstalled until this bug gets fixed. Running Windows 7 Home Premium 64 bit.
UPDATE: I used the aswclear utility from Avast and reinstalled latest version of Pro Avast. All seems to work ok now. Fingers crossed.
