There does not be a clear answer to this problem so here are some ideas.
Idea 1. Clear your browser cache
This link explains how.
Download the latest version of Internet Explorer 7 and any patches. I assume you are using IE7 as it does not appear to affect IE6.
Idea 3. Upgrade Windows XP to Service pack 2 if you don't already have it.
Idea 4. Use SFC to identify missing components and then install the file from your XP installation disk.
See this link.