RMagick and Image Manipulation

I'm having the same problem generating thumbnails (only I'm using
Magick::Image rather than ImageList). I've tried a bunch of stuff but
nothing seems to work so far. Incidently the problem seems to occur
regardless of the image size.

I'm probably going to resort to one of the following:
- a spinner gif and an ajax request to see if the image is there yet
or
- checking if the file is on disk before returning the generated
thumbnail path
(and manually blocking the return until the file is written)
both options make me cringe a little though....