Reinstalling IE8 probably won't fix it either.
Go through every setting in Internet Options and clear/delete/reset everything.
Then,,, go into Control Panel / Credential Manager
Control Panel / User Accounts and Family Safety / Credential Manager
Check to see if there is anything listed there.
Delete entries till it starts working again.
Don't know if that will work, but worth a try.
Also, note,, some secure websites will not allow you to save userID's and or Passwords.
It's a security risk to do so.
Also,, do you by chance have CCleaner installed?
I do recommend it's use, but only recommend the latest version.
Also see this http://blogs.msdn.com/b/ieinternals/...ems-in-ie.aspx