I don't know how much help this is, but I saw that two of the files, if viewed in raw data format, show 'JG' as the first two bytes. That would imply they are being saved as AOL art files, which I believe (without researching it) is a proprietary format. My guess is that it wouldn't be comprehensible to any browser other than AOL or some AOL client. My GUESS is that AOL mail servers are involved, yes? If so, they might be doing the nefarious graphical corruption.

SO.....

Now, I don't have Vista OR AOL to test with, so all I can suggest is that you might want to try the Firefox option.jaxom92 suggested.

You can get Firefox at http://www.mozilla.com/

Frankly, it's a better browser, but I admit I have severe anti-Microsoft leanings.