Thanks Marsianin
I did all that and my old notes data came up very nicely. Unfortunately, this morning I re-opened it and I am now getting a message "Error opening database. May be file is corrupted or opened in another copy of Mars Notebook".
I think it is the second of these. Here's what happened in detail.
1 - started Mars Notebook.
2 - started MS Outlook 2000 (I really must switch to Thunderbird!)
3 - started Mozilla Firefox
4 - Mars Notebook screen displayed with correct data on view
5 - MS Outlook screen started to display and built correctly
6 - Firefox screen overlayed Oulook - also correctly
7 - noticed that there was no icon on the TaskBar for Mars Notebook
8 - checked for any hidden icons with <Alt + tab> - found none
9 - started Mars Notebook again - and now the error message
10 - figured I could re-run the db-convert from my backup but I get one of those joyful MS error messages meant for the technically-smarter-than-me to the effect that Error Code 5: Access is Denied - Native Error 30361 which I suspect might mean that the destination file (that I tried to overwrite) is currently open to another program. And providing a different filename does in fact let me complete the file convert. And I can also now open that file in Mars Notebook.
Preliminary conclusion: for some reason the first instance of Mars Notebook exitted improperly without closing the current data file which Windows now thinks is still open to the application. So, next I closed down windows and restarted it to test this theory.
On restart I did the following:
1 - started Mars Notebook
2 - started Mozilla Firefox (to get to this bulletin board page)
3 - Mars Notebook screen displayed with correct data on view - from the alternate data file (which I had previously made a change to so as to distinguish it)
4 - used the About... screen to get the hyperlink to here
5 - Mozilla Firefox opened this website correctly and I navigated to the bulletin board form I am now filling in ...
6 - looked back to the TaskBar to find Mars Notebook had gone
7 - restarted Mars Notebook which now reported the same message as before
8 - tried to open the original file that had failed to open before and this time it opened fine and thus far has stayed open quite nicely.
So I think my preliminary conclusion is correct - that the error message is due to Mars Notebook having been terminated improperly and the file system thinks the file is still open.
What is not clear is why Mars Notebook terminated improperly. Later on I will try to activate it a longer time after system startup, as the problem occurs shortly after start up when, typically, all kinds of things are still loading and competing for memory.
I checked the application, security, and system logs using Event Viewer and did not find anything unusual that might correlate.
Checking in the Task Manager just now shows ONE instance of Mars Notebook listed under applications, but under Processes there are
TWO instances of Notebook.exe running. Closing Mars Notebook terminates one instance of Notebook.exe. I then terminated the second instance of the process Notebook.exe. After that I could run Mars Notebook again and both data files can now be opened successfully at will.
Conclusion: shortly after startup the application Mars Notebook terminated improperly leaving the attached process Notebook.exe still running. Further activations of Mars Notebook run correctly. (At this moment I have two full instances running concurrently each with an open datafile.)
Hope all the above helps.
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Besides all that, a really nice upgrade which I would like to thank you for.
All the best
Al