Just an updateto my problem, i deleted the Mcafe,Norton backup,microsoft office expired,,i reinstaled Avg, didnt work same problem, and then Avast , didnt work always blue screen. In the end i deleted all the antivirus , cleaned my Registry, and i installed THE WINDOWS SECURITY ANTIVIRUS. now my pc works fine with no blue screen.I guess the problem was that most of the antivirus do not work well with some of the windows 7.Thanks for your support.