You have wrong versions installed on XP
Follow these directions to uninstall reinstall ie8
http://answers.microsoft.com/en-us/ie/forum/ie8-windows_other/how-do-i-uninstall-and-reinstall-ie8/6ca5ef39-3a6c-4af8-a9f9-5bb821027772
this just happened a week ago and the comp is around 5 months old
i upgraded to IE 9 and was still having the problem