I haven't used the defines for a long time, but try creating a shortcut of your exe on the Desktop -> right click and open Properties, in the Target box, after the end of the statement, if there are quotes add after them (after everything) the defines (-nx 200 -diag). It should work.

Also, for your menu script, make sure you're not using filenames directly! Add bmap definitions. And watch out for pointers.
It shouldn't be a problem, but you can mess panels easily.

alibaba,
As for entity creations, I always group ent_creates for a lot of entities in one call. I mean, I call ent_create 10 times with a counter, for example, and wait one frame. This makes sure the engine wont 'stall' for a second.