Sounds like some malware if you restart in safe-mode and scan you should catch it. Why is reinstalling not an option? No disk?

I would also check folder c:\I386 for file labeled HOSTS open in notepad and see if there are any entries in their besides the localhost example microsoft gives you. This could have been altered with malware. Always make sure you know what you are doing before changing anything or at least make a backup. Also your IE could be corrupt, reinstall, i don't see the problem but here is the link to the IE homepage you should be able to get more information on updates for the browser at IE home page. Let me know.