7.1.0.9 paid / W10 error loop (I know; I'm old)

[Berten Ellay]

1. Something happened the other day where Eudora was not properly closed.
2. I have a large (~2gb) *.mbx file (let's call it DumbName.mbx)
3. I receive a regular error popup that states
1. "Could Not Read from file"
2. [.../the_filepath/DumbName.mbx]
3. "Cause: no such file or directory exists (2)"
4. Both the filepath and filename are correct and all my *.mbx are in the same filepath
5. I then click on "OK" on error popup
6. "Building .../the_filepath/DumbName.mbx table of contents"
7. Return to step 3

What I have tried
- I have opened DumbName.mbx as a text file and I see nothing wrong.
- I have "transferred" half the contents DumbName.mbx to another *.mbx, and compacted the mailbox(es)
- I have cut and pasted DumbName.mbx manually into two new *.mbx
- All the time restarting Eudora, with and without the original *.toc files in place
- Yes I have backups (thank gawd)

Any clue?

[DaveH2]

I'm assuming this isn't one of the system mailboxes (In, Out, Trash, Junk).
If you let one of those get that big, you would really be asking for trouble!
Personally, I wouldn't let any mailbox get that big.
Do you have a backup of the data folder from before the improper closing problem happened?
If you rename the present folder by adding .old to the folder name, and put the backup in its place, does the error message still appear?
If so, it doesn't look like the bad close-down of Eudora caused it.