Premanshu Bhushan,
You said it worked fine before the update of your computer. What kind of updated to your computer? The reason I ask is that I am having the same problem and it started for me right after I added memory to my computer. I tried taking the memory out but it didn't help. It's hard to believe that upgrading a computer can cause this problem. I too have run online scans, McAfee, Microsoft Anti Spyware, and AVG separately and they all say I'm clean.
But I am also having problems running Ad-Aware by Lavasoft. My ad-aware problem started at the same time my Spybot problem started. Is anyone else out there having an Ad-aware problem also?
Michael311