Bad stuff happens when PHP runs out of memory

On a PHP installation with a 16M memory limit set, I caused a problem where fetching a full size image (along with several others) resulted in a memory fault. Because of this, the Bluga WebThumbs module thinks it already downloaded the file, but the file is 0 bytes long, which isn't very useful.

I would like to avoid a situation where such a memory fault results in repeated attempts that will just cause the WSOD to appear over and over, but I would like there to be some sort of work around. This might be as simple as checking to see if the file exists and trying to fetch again if it does not. This would require user intervention, but is less work than requiring someone to go mucking around in the database tables to make sure the image is fetched correctly or using something like setting $refetch to "always" and using another token needlessly.

A work-around as is, would be to log in to your Bluga account, download the image by hand and drop it into place.