I have a clue re my problem.
The crashes and malfunctions appear to be related to the addition of a text list to the database. It was a single column, no duplicates, database navigator, list.
I discovered this because I made a new version of my database from the Pan6 version. I deleted all forms and all programmes, stripping it down to raw data. Then I started adding forms back in. I’d come up with the idea of using one of these lists on a form, to save me creating an extra form. When I created it, the programme immediately crashed. Although it hadn’t been the last thing I’d done with my other database, I thought, in retrospect, that was probably when the crashes started occurring, (ultimately progressing to complete non functioning of the database). I managed to open my old corrupted database, deleted the 2 lists I had put in, and it started working normally again.
I have used similar lists elsewhere - but probably also with frequent crashes - and never got into this much trouble with it. However, the fact that it happened in both versions of the database makes me feel it is an internal error.
Hope this information helps you sort it out. I’ll play a bit more - probably try to get the list working with a variable rather than navigation, and keep you posted on what works/doesn’t, and keep you posted.