Sounds to me that ur downloading something... do u run limewire or any sort of downloader software?
I would unplug my computer from all its connections, and leave it off for awhile. Maybe overnight... then reboot her in the morning. Go through ur "control panel" and look through applications that might make a difference.. such as 'accounts', which it sounds like uve already done. ALSO press control alt delete and open the "task manager" and it will show up what exactly is running on ur computer. It will tell u down the exact operation and program, maybe even how much capacity its pulling. Find any suspicious programs or applications, and shut em down. Be careful because u dont want to wipe out something important. but investigate. goodluck!