it was all ok until today, everything was running well
today the Internet stopped working, the firewall could not turn on,
i did system restore, INTERNET started working back, but my avast which was v7 updated, rolled back to v6(normal to happen) but stopped working, shields cannot start anymore, firefox doesn't start, avast installer doesn't work anymore either

Uninstall firefox and all old/broken antivirus/antimalware programs.

Reinstall avast

Run avast boot time scan (quarantine or delete all detected objects).
http://download.cnet.com/Avast-Free-Antivirus/3000-2239_4-10019223.html

Download, install, and run Emsisoft Anti-malware (quarantine or delete all detected objects).
http://download.cnet.com/Emsisoft-Anti-Malware-Free-Previously-A-squared-Free/3000-8022_4-10262215.html?tag=mncol;2

Download, install, and run HijackThis and post the report here
http://download.cnet.com/Trend-Micro-HijackThis/3000-8022_4-10227353.html?tag=mncol;1

Good Luck

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