http://code.google.com/p/fpscreatorengine/
this is where you can go to the tgc issues and leave the problem with them
need to sign up but do not give in before that try this, i have, and tell them you have nearly given up etc and they will give it a shot hopefully.
and maybe it is too larger map i do not know as i have not seen it
are you on a 32 or 64 bit machine, as 64bits do have more issues than 32 bits
i do think its the code though and are you using mystic mod or original?
best be on the basic 1.11 orig and try a smaller map with lights, bestthing is leave your created maps alone and do basic tests from simple room with a light to 2 lights then 3 etc. and find out what maximums or minimums or if any at all, because mine does many lights and quite big rooms too. but let me know anyway
s.sb
an unquenchable thirst for knowledge of game creation!!!