defragging just reorganizes your files so that the HD doesn't have to take so long seeking it. But if you have formatted lately, there shouldn't be a reason to defrag since everything was wiped.
Man other than that stuff, I have no clue what it could be. Maybe try updating or upgrading the version of IE. You could also try downloading Mozilla Firefox or Opera web brwsers to see if if works fine. If it does, you know it's an IE problem