Go to www.download.com and search for a program called Ad Aware *it hunts and gets rid of spyware and adware that can infect your computer through websites*, too many spyware files could be eating system resources. *I hate spyware *

Ad Aware is free to try, and the free version really isn't all that limited.

Also, a disk defragment couldn't hurt. Id also scan for viruses just to be safe. If you don't have a virus checker, a good one is AVG for windows. It is free and it doesn't miss ANYTHING

http://www.grisoft.com/us/us_index.php