just to confirm, did u use the Avast! uninstallation utility? standard windows uninstaller is not sufficient to remove antiviruses. a complete uninstall is needed to ensure problems with previous corrupted installs are eliminated.
if u did not run the uninstallation utility follow the following steps.
1. Download a fresh Avast! 7 package from
http://www.avast.com/free-antivirus-download (to reduce chance of corrupted install)
2. uninstalling Avast! the normal way with windows
3. run Avast! uninstall utility
http://www.avast.com/uninstall-utility (please do it in SAFE MODE! )
4. run the uninstall utility (2 TIMES) total, one for Avast! 7
5. reboot and go into safe mode once more, second time for Avast! 6
6. reboot again, this time to normal windows mode
7. install the fresh package
8. please report ur findings here =)