I've been seeing this problem with avatars/photos for some time now. It's really starting to bug me so I checked over here and see that others are having the same exact problems. Avatars are scrambled, photos don't show correctly and when I refresh the page to straighten the pictures out, it's like playing a slot machine...you never know what you're going to get! Clicking on a photo in a cache log most often ends up never loading.
Don't know if it will help, but I'm using Windows XP Prof SP2 and IE8.
I hope you can figure it out soon. It's starting to get very frustrating.