My pc's been giving me trouble since the last 2 or 3 days. It freezes for 5 to 10 minutes then starts functioning as usual but slower. I have noticed thanks to the task manager that the problem is that the disk access goes up to 100% so the programs have to stop responding. The thing is that when that happens, task manager doesn't show any process doing disk operations, or at least not ones that would take it to the 100%. My question is that if there are any processes that the task manager doesnt show or something of the sorts, so I can find the source of the problem and with any luck solve it.
I am almost certain that I have been infected with some trojan or worm that is "clogging" the disk access so I have run several scans with my antivirus (Bitdefender) but with no results. I am (unfortunately) running windows 8.

I hope you guys can help me. Thanks in advance

P.S. : Sorry admins, I didnt know where to open this thread so feel free to move it appropiately.