I have this exact problem as well. After using aswclear.exe, deleting program folders, using a registry cleaner, and performing several clean re-installations all in safe mode with reboots in between every step, I have been unable to get avast! 7 to operate after rebooting. Avast! 7 works perfectly immediately after installation. But, after rebooting and logging-in, my system returns the following error.
Msg: AvastUi.exe - Application Error
The exception unknown software exception (0xe06d7363) occurred in the application at location 0x7652fc56.
After clicking "OK" this message immediately reappears and sounds the "avast! virus database has been updated" notification several seconds later. I can repeat this indefinitely with no change.
I have Windows Vista Home Premium 32-bit.
Thanks, Trevbob