I suspect it was affected by some of the security patches from MS. Last I saw, parts of it had been re-routed to System 64 file folder(Good hiding spot on a 32 bit machine!!). I suspect "The Idea" was to force you to upgrade to newer(more secure?LOL)versions.You don't say if you're SP2'd yet.
There is a program called: IEFix.Exe which you can Google for and download (free) and run but it may ask for your install disk ( for additional files). If you are SP2'd it may ask for that disk or the path to Sp2 file folder. Hope this Helps some.
Does XP have a repair Internet Explorer feature like 98SE did? Thanks,