Okay, figured it out… I use the Retro Replay fastload and it's very rare for it to cause any problems, so took me a while to even remember it… Works fine (although very slow :-) without it.
So, all good – thanks for the help and sorry for the trouble :-) I have two saves on the disk now, so I guess I'll just keep using those two as I don't need any more.
Might be useful to mention both the turbo loader issue and the save disk details in the readme?
Cheers!