Is the size 513x513? Is the image grey scale? Have you flatten the image (No multiple layers)?
If you haven't did one of those, then it's why your FH crashes when you type in the height map name.
Have you put spaces in the name of the height map? That will definitely throw it off. Also, if you have layers in your picture that will also make it crash. If you are using GIMP or something similar, what I usually do is copy visible and paste it on a new page then overwrite the old height map. If this does not help, let me know and I shall do my best to figure it out. ^^
Is the size 513x513? Is the image grey scale? Have you flatten the image (No multiple layers)?
If you haven't did one of those, then it's why your FH crashes when you type in the height map name.
Ill try both of these and see what happens