But this should not be happening. I had a similar problem a few weeks ago, and had to do a thorough virus scan and as it turned out my comp was infected.
http://housecall60.trendmicro.com/en/start_corp.asp?id=scan
Or maybe this is a better link.
http://housecall.trendmicro.com/?WT.TM_clusty_flg=7
This cleaned it and now the comp is running fine.