Ok- a couple of quick things I'd try, given that it's only your current account that's having problems:
1. Log in as an administrator, create a new user account, log out of the administrator account, and:
a) log in to the new account and verify that all of your programs (including Internet Explorer, obviously) work properly. If they do:
b) Log out of that account, log back in under an administrator account, and copy the contents of your C:\Documents and Settings\Old_Username folder to your C:\Documents and Settings\New_Username folder (instructions for doing so are
here). If you get prompts asking if you want to overwrite existing files/folders in the New_Username folder, click Yes.
c) Repeat step "a)".
If all seems to be well you can delete the old account, although I'd leave it in place for a while just in case.