If you want to investigate what's running on a background, you can do following:
Download
Hijackthis utility. It's small.
Lanch it. Click on Config... button, then Misc Tools. You'll see Generate StartupList log button. Make sure that option List also minor sections (full) is enabled. Now click Generate StartupList log button and you'll get detailed log of starup apps and processes in a notepad window. Save this log to txt file and attach it to your reply on this board. Probably together will be able to find the source of your problem (if it's not a hardware problem of course).