Access 200 Permission Lockup

Either when copying from one db to another on my machine or running a db produced on that machine on a network, I get the message "the database has been placed in a state by user (my machine is called "Rat") that prevents it from being opened or locked". =Error 3734.
The security data says I am "Admin" and permission is set for Admin and Users. It has been doing this intermittently for a while and now does it all the time.
Follow up data
All databases are created, revised and run on home machine (Rat) and run on the office network.

The offending DB will permit internal design, editing , copying and will accept pasting IN of tables etc. from other DBs. But it will not allow copying OUT of files such as a table to other DBs even on the machine that created them. However it will allow copying and pasting of objects such as forms in visual form or individual query cells to other DBs.

I’ve carefully compared the Tools/Security/User & Group Permissions with a good running version of the DB and can see no difference.
Permission settings on good and bad DBs are:-
Permissions: Admin Object: Current DB
Checked: Open/Run, Open Exclusive, Administer.
I’ve also checked each individual files’ Permissions. The .ldb file, viewed with Word with the offending DB running on my office machine (Weasil), reads:-
WEASIL_ Admin_

The creating machine “Rat” uses the Account “Richard”: but I have had few similar problems before. While revising the DB, I made 30 copies of at each stage along the way but saved carefully each design change and certainly did not deboot the computer without doing so.

I’ve tried the above procedure on my computer (Weasil) at the office, but got the same result. So it’s not the computers or MS Access 2000 program. Somewhere along the line, perhaps, the DB got corrupted. It Repaired and Compacted OK but still has the problem.