Hi Mel
Where are you going to for depth under keel?
You can either use the icon, bottom left corner.
You can ask the Navigator by selecting the Depth Under Keel icon.
I cannot see anything in the the GFP that would cause your ctd.
I am using the GFP and have never had this problem.
The only problem that I am aware of is sometimes you get the pings and no verbal response.
Have you tested Depth Under Keel in a Historic Mission?
Do you get a ctd every time?.
Peter