Here do this... Make 4 Square (solid) boxs over your map so your map is completely covered, then delete one box. Try compiling. If it says theres a leak... Click undo to make the box reappear(within this box is where your leak is) Delete the other three boxs, and compile. There shouldn't be any leaks (since its covered within the 1st box)
Now make this box a little smaller and compile.... if you still don't have any leaks then, you know the area you uncovered is'nt where your leak is. Make the box even smaller, covering less of your map..
Continue this until you have a very small block. Delete the block and there.. you found your leak!