A. Hard drive or virus problem
B. Hard drive or virus problem
C. Spyware problem.
D. Hard drive or virus problem.
First, I suggest you run a brand new clean copy of a strong anti-virus program, then a separate anti-spyware program.
All of these problems can be a result of a nasty virus.
(Anti-Spyware and Anti-Virus mix programs tend to miss a lot of stuff, and are usually buggy.)
If both scans from both programs come clean, you probably either have a deadly nasty virus, or just a buggy hard-drive.
Before you do anything, run a disc defragmentation.
If the problems still persist, you either have a nasty virus, your windows is going bad, you are running windows 98 (In which case you call the bomb squad) or something I can't identify is going on.
Most nasty viruses stick themselves in the deep part of your hard-drive, and can only be removed by a reformat. Just a windows re-install will just jump the virus back on your system, so you are going to want to do a re-format to be sure.
If problems still persist even after a full reformat, I would toss my hard-drive out the window, beat it with a hammer, burn it, melt it into liquid, dump the liquid in orange juice (or coke), freeze the orange juice (or coke), and toss it in the lake.
Who will die first?