There was a problem with the software that caused thumbnails of uploaded images to be corrupted - shown in grey-scale only, or not visible at all.

The problem has been fixed with the new software, so any newly uploaded images will be handled correctly. However the broken thumbnails for images that already existsed need to be fixed by re-uploading the image.

I've fixed a few that I could find, but if you see any others that are still corrupted, just drop me a PM and I'll fix them aswell.