taken over the png file extentsion on the box that won't show them. ah, no,
wait. if that's teh case, the nutscape wouldnt' work. hummm... when all else
fails, you can always install ie5.5 again to see if that helps?
You can also look in file associations on one of the machines taht works and
make sure that machine that doesn't is setup the same for png files.
HTH, good luck