I have an installation of MT that I've used for a long time, and has quite a number of different blogs on it. (It's version 4.3)
The newest blog was a clone of one other blog, as I planned to spit the original blog into two.
After cloning, I uploaded some new assets to the new blog, and now assets cause a 500 internal error. The error pops up when I try to upload or to manage assets on that blog.
The manage assets area on all other blogs is fine.
The system overview manage assets is fine on page 1, but gives an error on page 2.
Does this mean that one asset is corrupt and is causing this problem? And if so, how can I fix it or delete it? I'd even delete all assets from the new blog, as I could re-do them if I had to.
Reported on Movable Type 4.3

Well, I'll answer my own question - it WAS a corrupt image, whether it was caused by Image Magik or not I don't know, but I edited my config file to use ImageDriver GD, and I could see the assets - and the most recently uploaded one (and its thumbnail) had a total size of 0.