this seems VERY much like me own problem. I was using AVG (
www.grisoft.com) and decided to try AVAST!. Sounds GREAT but quickly locked up my pc... dads pc.... as well as my work pc !

The only way to access any program
I had to start in safe mode and uninstall AVAST! then reboot. I finnaly have control of all my pcs again. I had uninstalled AVG and ran registry cleaner to cleanup any entries(before installing AVAST!) that may have been left behind by AVG.
Strange thing about it all is AVAST! worked great for 30-40 min. then locked up solid. Reboots never helped...just locked up instantly. So I dont really know what is causing this problem. I have just re-installed the program again

( am I asking for trouble

?)Hopefully TECH SUPPORT will correct it soon...very soon.