Hi all,
So, after a lot of slow testing I've found the problem - it was with the Access DB I was using.
I went back to the last working version and tried removing the control and all was well.
I then updated the code slowly toward the latest version and all was well.
The last bit of code change required the latest Access DB, so I went and got it from the directory with the failing code it, and it failed again
I went back a version and took the old Access DB and hand modified it to the required state and all was well.
I have absolutely no idea what was wrong, but it all works again now. I did do a clean and repair in the 'problem' DB, but that didn't do anything.
So anyway, problem fixed.
Thanks
Dave