Does IE start under Safe Mode? If so your PC maybe infected.
When you start your PC, keep hitting F8(?). This should bring up a preboot menu. Select Safe Mode without networking. When Windows starts up attempt to run IE. If it works see if you can open up some web files on you hard disk. Real Internet will not work under these safe mode conditions, but locally stored pages will. Do a C: search of your PC for html/htm files.
If IE starts and displays these pages, try uninstalling any IE add-ons you may have installed (as suggested above). Also do a full virus scan (with latest updates), full spyware scan (Ad-Ware is good), and also download McAfee Stinger (do a google).
I suggest you download all these before you start in Firefox or Opera, then do as above in Safe Mode.
Tell us how you get on...
Alex