[monkey]

Well I have been using these programs for very long (about 2 years now) and never faced any problem. AVG Free generally works with any paid AV without any problem. I have basic Sysmtem Mechanic without AV so it can't cause problem. I had removed AVG before thinking it to be culprit but it had no effect and so I installed it back. Other programs are generally the one I use regularly (GTalk, YPOPs, Nero...). Like I have said earlier "why the problem occured now when I have been using these programs for 2 years now?"

@Pathik: I can't format Windows as I have genuine copy of Ad-Aware which will need new license everytime Windows is installed fresh. I have already acquired license twice in the past 2 months from Ad-Aware guys (once when I upgraded my hard disk and once when Windows had developed some problem). If I ask for license again then Ad-Aware guys will shoot me