Since updating to new free version a week ago it sometimes does not start on startup and windows vista tells me I have no antivirus protection. Rebooting a couple of times solves the problem, but it keeps re acurring. This never happened with older versions. Any help please or should I revert back to older version?. Thanks.
try a new clean install
Uninstall Utility. http://www.avast.com/uninstall-utility
Installation files. http://www.avast.com/download-software