you got any mods runing? outdated mods (not updated for specific use with V1.03) will cause crashes when you try to play them.

did you try making a new map and making sure it has the same version number (1 for 1.03) if that fails, you could try reinstalling but i doubt that is the problem. It would seem that allot of people have problems with maps in 1.03, so far the main causes i have ran across is mods and the map version number. i reinstalled my game personally and i don't seem to have any problems now with the maps, custom or otherwise (although i always edit my custom maps to play with mods) you could also try re downloading galaxy forge, i read somewhere that it is suppose to be 1.03 computable now and then trying to make a map (unless you use the default map generator in-game).

hope it works for ya, good luck