i've tried to uninstal avast with Revo and your uninstaller, i can't get rid of the entry in start up, so it won't let me uninstall it completely and it won't let me reinstall it
i tried ccleaner and mscnf with no results , i'm not expert enough to go into registry
i want to put a new antivirus so i'm uncovered until i solve this
Really you should only uninstall security-related software such as an anti-virus, anti-malware, firewall using the programs own built-in uninstaller rather than Revo Uninstaller, etc., since most have to unregister/unload resident drivers, etc., and also look on the software website as they'll typically have an uninstall supplement if uninstall fails.