Hello Brandon & Tony. Here's what I did, and it's happened twice for me so far.
Created a folder #1, imported about 200 photos.
Created a folder #2, imported selected pictures (about 25), modified a few (no saving done).
Created another folder #3, imported selected pictures (maybe half a dozen), modified one or two (no saving done again).
Decided to remove folder #2 from Library - completed successfully.
Removed folder #3 from Library. The dialogue box came up - "removing" - then it said "done", but the little icon kept going round and round as if it wasn't finished. Nothing would respond in the program, although the rest of my system was working normally. Opened Task Manager, viewed running tasks, it said the program was "running" (no "not responding"). After waiting a few minutes, still no change, so I ended the task. At that point I got the "do you want to save" dialogue, and said no.
Upon reopening the program, the folders were indeed gone.
Win XP Med Ctr SP3, AMD Athlon 64 Processor 3500+ 2.2Ghz, 3GB RAM, 890GB C:\ partition with 670GB free.