illegal pages open

Dear Sir,

I am using windows 2000 server. recently very strange things are happening with my pc. there is one icon at task bar called “Music Search Online” i am unable to remove it from registry and pc. also when i am working some illegal pages get opened inbetween which contain nude photos of girls. when i open my internet explorer it automatically open page http://tefs.com…
like that.

How to solve this problem

Please help me !