Got the latest version running well on my Dell Inspiron laptop but when I did the internal update on my Dell Optiplex GX270 desktop (XP SP3 fully patched) the system froze. Booted into safe mode and uninstalled Avast using the Avast uninstall utility and tried to make a fresh install from a new download–same problem, system locked up. So there went most of my Saturday; uninstallled Avast again and finally got the desktop working fine but now I have no AV. Don’t know what my next step should be. I’ve used Avast for a long time without serious issues but the latest version just won’t run without locking up my system. It’s allowed and trusted in my firewall (OA) and I can’t figure out what else the conflict might be. Any advice would be most appreciated.
Similar problem here, except that I’m running Vista (64x bit) on a Dell Studio. Had to do system restores to be able to get it back running. 
I’m not a recovery guru by any means, so I’d really like some help on this one.