Kintin, get an apple mac!!!
OK, so your stuck with windoze, like I am at the office. I agree with Tony, it sounds serious and its not cache.
You could always return your operating system to a previous saved point. Do you realise that you can 'go back' a few weeks, and restore the whole XP to where it was before you added whatever programs you added? Search on 'restore' under windows help.
Just backup anything that is recent and important.
This process will prove whether its you or the server with the problem.