Still not sure about the security token error... I mean it's a value that gets passed through various forms in vbulletin, that they introduced over a year ago, but I don't see why it would be broken.
The failed uploads, though... could it be the jpegs are too big?
“The egg hatched...” “...the egg hatched... and a hundred baby spiders came out...”
“Who are you?” “A friend. I'm here to prevent you from making a mistake.” “You have no idea what I'm doing here, friend.” “In specific terms, no, but I swore an oath to protect the world...”
“It's a goal you won't understand until later. Your job is to make sure he doesn't achieve the goal.”