Boat Travel ceased working

For some unknown reason the boat travel, both within the original Quest game and to its expansions has ceased to function. Trying to travel by boat causes an immediate crash of the game.
This occurred after finishing the Cursed Chess Set expansion and trying to travel by boat from Mithras to Matras in the original game (to take a boat to the Celtic Rift expansion).
Any ideas?
DMB

I suspect disk corruption. If you are on Steam, try verifying the integrity of game files. Otherwise try reinstalling the game. (Copy your save files to somewhere safe before, see here.)

Thank you very much. I am on Steam and have tried verifying the game files and they seem OK.
Looks like uninstalling and reinstalling the game. Thanks for the tip on how to copy my saved games.
DMB

Elendil
I have uninstalled and reinstalled the game from Steam.
No joy unfortunately.
The reinstall brings back all the save files, so I tried deleting them and uninstall/reinstall.
The save game files came back when I reinstalled the game and it still crashed on trying to travel by boat.
The only other odd thing is that the last 2 expansions I played :- Ragnar's Revenge and Cursed Chess Set are not on my list of curated expansions.
Now at my wits end.
DMB

Elendil
Thank you for your help. I think it is time I stopped pestering you.
It looks like my problem is unsolvable, it could be a problem with the computer itself.
The Quest is my favourite game (and my wife's) and I have decided to keep it uninstalled from Steam and buy it and its expansions from GOG and hope that a different platform will solve the problem, why it suddenly occurred after 8 years of both it and its many expansions working perfectly I have no idea.
Once again thank you for taking the time and trouble to assist me with this matter.
DMB

You said you haven't installed all expansions? When a save file is created, it stores all installed expansions, not just those you actually travelled to. After that, you'll need them installed to load that save.

The game should notify you of that fact (something like: "The save you are trying to load requires expansion(s) which are not installed.") and not crash but it might think they are installed when they are not for some reason and then crash when trying to load things from them.

Thank You again
As far as I am aware I have got all the expansions installed, its just that 2 of them are not showing up on my list of curated expansions. The odd thing is that from the saved games I can travel to and from these expansions using the Mark & Recall spells.
DMB