Every now and then--and this depends to some degree upon the quantity and types of software you've installed--it's a very good idea to re-format and reinstall things. Sort of a pain, I know. But think of Windows as a great big sofa. After a while, loose change, cat hairs and dead spiders accumulate under the cushions and you need to clean things out. Also, I believe it would be worth getting the most current version of IE: it seems to be a little more stable than earlier versions.