I had a google for "missing images" (I did not add the quotes for the search.)
Heaps of responses of course but a possible new line of enquiry for you is what Microsoft have to say on this page
http://support.microsoft.com/?kbid=283807
Most is routine stuff, like switch images back on
but there is a bit about "Internet Explorer cannot determine the character set"
Perhaps, if as Microsoft suggests " ... a file or registry key required to display the Web page with the appropriate character set may be missing or damaged" and assuming the same key is used by all browsers (I have no idea!) then the problem could happen with any browser on that machine.
Let us know what is was when you crack it!
Memetic