A current and as of yet unresolvable issue we're facing with the forum right now is uploading images as an avatar to the system. You may have noticed this by now by attempting to upload from your computer or using a direct link from a URL. What you'll need to use instead is link to an off-site location and submit from that option. It would seem there's no other way for now to alleviate the issue, so you'll have to take this detour method for now until Forumotion can fix this.