OK...taking another approach. I tried manually downloading the cat_thumb.jpg file:
cat_thumb.jpg
It downloaded, but it took a long time - something on the server side, not my side -- maybe a GD issue?
Anyway, after caching that image, I was able to load the whole gallery without any trouble.
There is something different or wrong with the file:
/gallery/files/8/8/2/3/cat_thumb.jpg
...in combination with IE5.5
Confirmed: without cat_thumb.jpg, the page load hangs, with the file cached, the page loads normally. Something is up with serving that thumbnail to IE5.5 simultaneously with others...