what Operating system (OS) do you have on it? If you are currently not using some flavor of Linux, you could try using a live cd. you can choose several, I personally like Ubuntu (found here). the downside to that is you need to burn an ISO. thankfully, there are free ISO burners, one of which is found here.
You now restart with the CD in, and you can run the OS completely off of the CD. after using the live CD for a while (it may be a bit slower then installing it due to running off the CD instead of the hard drive.) and not re-creating the problem, it is now narrowed down to the OS you have installed on your system.