Cobra1117: In all likelihood you'd have experienced your edit 2 case with FastCraft installed as well, regenerating just fixes the corruption in any case. Since MC doesn't normally save the world after/during a crash, it was most likely already corrupted before you had the original crash. I've put some protection against crash related save corrupted into FML a while ago, so this is to be assumed more complicated than you suspect.
Cool. In that case I'll put FastCraft back on the server. Thanks for the info!