I’m not using any unusual objects and I have no leaks, just brushes and a standard everyday Entities (no vehicles), but my compiling window freezes when it gets to this point:
http://img203.imageshack.us/img203/4104/argcompilealready.jpg
I let it keep going for half and hour, and nothing happened. Once I closed the window and Hammer crashed (as it seems to always do if you quit in the middle of compiling), my 4 cores all shop up to 100% and the computer was barley moving. This happened twice so far with the same result. :S