Feral Heart

I have been trying to make a map forever. I've followed tutorials SEVERAL times, And i have a large map. I was able to put it into the map maker, and work on it a little before it crashed, and then it constantly crashes. Now, I have it No alpha channel, One layer 513 by 513 PNG image, and it worked for a while. Then it began to crash again. Not constantly but after a little bit of working on it BAM! it crashes. I  then, re-installed Fh was a bad idea when i began to crash just loading the map up in the map-maker. PLEASE HELP!!! I've tryed making it into a new file to. It dosent work! PLEASE help me!