hm.... maybe you have old computer....
btw mine c2d 2.0 2048 Mb RAM 512Mb GeForce 8800M Go to Theramore isle and manipulating with many WMO-s without any error! While pressing "C" there is no errors!... hm... Try to install GTK
edit: ok! I found "c" error.... you pressing "c" when current selection is WMO or MDX!!! huh ok it is very easy to repair =))) at next release!
btw... MapChunkSettings window is still passive! So you no need them at all! Maybe at next release it will be active with chunk manipulation functions without any error!