I have just been informed that there are HUGE errors in the Perfect Dark mod's source code. In fact, the only thing that appears to work at the moment is the gametype "Pop a Cap". Turns out that there are about 400 Accessed Nones in the log file after you run it, and the game will crash if you try to play any gametype except "Pop a Cap".
So now, incredible as it may seem, a simple deletion and recompile has fixed the entire thing. So.....an updated .zip file with the fixed .u and .int (don't know if .int caused part of the problem, but just to be sure...) files is availabe on the files page, or by direct request at the link below.
Sorry for any inconveniences/frustrations this may have caused.