I right-clicked on a slide to delete it, and after a few seconds, Proclaim crashed: "Failed to decode image. ~OutOfMemoryException: Insufficient memory to continue the execution of the program."
7737.Proclaim.log
According to Task Manager, Proclaim was using 929.9Mb after the crash.
When I restarted Proclaim, the slide had not been deleted. I was able to delete it the second time, however.