Blue Box with White Question Mark On certain websites (minecraftforum.net) most images appear as a blue box with a white question mark in it on safari. On my school forums (private to the school only, so can't link) normal images work fine, but an animated GIF generates the same blue box. The images do not load in chrome or firefox. Anyone know why?

I have safari 6.1, I'm on a MacBook, and I'm running osx 10.7.5
When you access the school's forums, are you on a VPN? If so they may be filtering larger files, as suggested in a comment.

This animated .gif file works fine for me in Safari. Make sure its not working for you before we go looking for local causes to your problem, rather than forum or gateway problems you and others have alluded to.