Had a page with multiple animated gifs on it. If the two image resizes start in the same second some frames from each image get incorporated into one image and the second image resize will fail completely. This is because each frame is essentially saved temporarily as frame_".time()."_".str_pad($i,2,"0",STR_PAD_LEFT).".gif" This is probably why refreshing the page would sometimes "fix" broken gifs in my case. Not relying on a timestamp as part of the temp file name fixes this issue. An md5 hash works great.
In the Libary had to change Line 68: