Unfortunately I had to remove avast 5. It was working OK until I decided to open Firefox, (usually I use Opera browser), went to a place to download a movie, internet download manager started downloading and suddenly all pc started to freeze.
I tried to disable module by module but it did not help. What helped was to disable Avast completely. After that everything came back to normal.
I have installed 4.8 now no problems with that one.
Hope everything is fixed up. Good luck. 8)