That doesn't sound too nifty; it certainly isn't a basic task. Is it System or you?
Do you have any Firewalls, Anti-Viruses, Special Writing Packages - although I doubt it could be anything like that - just doesn't sound right!
Installed any dodgey stuff? Divx Player? I don't know any more off the top of my head!
If it were me, I'd just reinstall Windows! But thats just me (I like sorting out the system and installing all the updates! I'm really sad
Installing Windows again is not too hard, or indeed arguous, but it always has to be a last resort!