i would say that reformatting your computer could be the last resort. You can still save your computer w/o reformatting.

If you have a Norton Antivirus then that would perhaps solve your problem. The virus that may be lurking inside your computer right now is the IST viruses. They come in all sorts of forms. One of which is the IST bar in your Interner browser. If this bar appears in your IE screen then you are infected with the IST virus that hides in some other parts of your computer.

Update your Norton then scan somputer. It will eliminate all these IST viruses. Norton may ask you to run your computer in the safemode but don't worry 'cause it will lead you to its technical support site which will give the step by step procedure