Sorry for replying so many times, but I made a new HD image, ripping the ROMs myself (the first one I cheated by using files from JOTD's WHDload image), and tested again on my A600GS.
Ending D still crashes, this time it just exited back out to the A600GS menu.
Ending B & C both WORK, going through to the ending as normal.
I am still working on getting to endings A&E, I've found playing what is effectively the arcade version with digital controls (as opposed to steering wheel or even analog stick) is downright hard.
I'll keep you posted if I get ending A&E.
Oh, and I played to ending D 3 times on UAE, and one of those times it crashed there too.