That happened to me a while back, I couldn't see any photobucket pics and then all of a sudden I could. It did it again about a week ago too. I'm not sure why exactly it does it.
ooo, I had that happen to me. Right click on where the pictures should be, and then block images from chazhound.com (actually, you should see a checkmark next to it, and by clicking it again, you should be able to unblock images)
Yeah, the reason signatures show up but not avatars is because people host their signature pictures on a different host, like photobucket. If you right click on a sig and click on "block images from photobucket", you won't be able to see (most) of the signatures.