system
5
Your last post was unclear to me (to say the least), and there is not much concrete info about your problem for anyone to try to solve it, whether it is a bug in Avast or a problem in your system.
You can try downloading a previous version from filehippo.com, but I suggest also running the removal utility of Avast under Windows Safe Mode to REALLY remove every previous remnants. Moreover, I would reboot into Windows Safe Mode twice, so to run the removal utility again for older versions of Avast that you had before (like once for 6.0 and one additional run for 5.x). If you run it twice, please don’t skip the reboot between them, and select the correct folder for Avast.
BTW, for other security tools that you ever HAD, you should run their respective removal utilities too (specially with the behaviours you described). http://thewebatom.net/uninstallers/security-software/