Have your tried updating to Internet Explorer, version 7.0? You might try this and see if the problem is resolved. If you decide you don't want to keep IE 7.0 you could uninstall after the install, assuming the problem is corrected.
Another thing to check this Webpage from HP about resolving IE problems:
Fixing IE in Windows If the linked section doesn't help, scroll to the top of the page and look at the other links listed there.
I didn't see where you gave us the Make/Model of your system, so this link is "generic" in nature. Entering your system information in the search will help narrow down the steps.
If you haven't tried using the online chat for assistance with HP products you might give that a try. I find that is a useful help tool.
Also, I doubt that it is really necessary to reinstall the whole system. I think you should be able to repair this important element of Windows.
I hope something here will help.
Dwight