your computer could just need a little clean out. here are some clean out tips.
1. Empty out your cookies, internet files, and cache.
2. Clean out your temp files, do this by going to C:\WINDOWS\Temp and then delete all the files there. Do not delete the folder.
3. Run a disk clean up. go to start, all programs, accessories, system tools, disk clean up. follow the rest. check what ever needs to be checked.
4.Run a disk defrag. same thing as step three except click disk defragmenter.
5. You might have a virus or spyware, whatever it could be. run your anti virus and do a full scan. then you might want to run another program called Ad-aware. I think i told you to do this in the last solution, just search it in google.
btw, im moving this topic to computer and tech