I realize it shouldn't, but it is doing something strange.  I have added the following pattern to my config, and it stopped parser errors with URIs such as:

/wp-content/uploads/2010/12/image.jpg

URIPATH2 (?:/[A-Za-z0-9$.+!*'(){},~:;=#%_\-]*)+

I can provide log lines and configuration if it would be helpful.