I was having a number of serious problems with WPC hanging in the middle of a category synchronization operation. After a large amount of detective work (I could really use better error reporting and progress reporting during the synchronization task so I can isolate where the problem lies), I found a directory in the search path that had a large number of Real Audio and Real Media files (.ra and .rm). I'm not sure why it was hanging instead of simply reporting an unknown file type, but you might want to check that out.
I've worked around the problem by adding .ra and .rm to the list of ignored extensions. You might want to consider adding those for the distribution version.