Seems like there's something(?) in the map that Mohlight doesn't like.
Okay, a couple of questions:
1) Is it a very complex map, meaning lots of brushes with lots of (manually placed) pointlights nearby?
2) Have you checked the map for bad polygons (malformed brushes) before compiling?
3) Can you compile the map without Light, without other errors?
If you haven't already, download the
Rogue-plugin. Place everything in a folder called plugins in the MOHTools folder. Then in Radiant go to Plugins in the menu and perform some checks.
Another thing you could try is compile with an additional option in the Light-stage,
-nogrid
"-nogrid: Don't calculate the entity lighting grid. (The lighting grid is used to adjust the brightness of entities, even when they move around, such as the player's gun getting darker in shadowed areas)." <-taken from the
Advanced compiling tutorial (in General tuts section)
I have no idea what the problem could be, never seen such thing in the lightstage before. But maybe the compile will finish when you use that -nogrid option so you can check the map ingame for any visual errors.