Just noticed that the
T-Shirt Gallery reports....
Cache directory needs write permissions. If all else fails, try running:
chmod 777 /var/www/boulder/media/t_shirt_viewer/resources/cache
It doesn't stop the pages from being displayed though.
I'd be wary of setting those permissions though, it means everything in that directory is then executable by any user. Depending on the owner/group settings on the directory (you can see these with 'ls -l /var/www/boulder/media/t_shirt_viewer/resources/' ) the following may resolve it more securely...
chmod 774 /var/www/boulder/media/t_shirt_viewer/resources/cache
Or since it works it could just be left alone, I doubt many people view those anyway.