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?
Imagine a pathologically idealistic, anti-religious, culturally-relativistic, iconoclastic, socially-irreverent, sociologically-progressive signature line here. Or don't.