The symptoms indicate that your database is partially corrupt.
Firstly, make a copy of the mdb file while it is NOT in use, and without
overwriting any other backups you have. This way you get multiple tries at
fixing it.
If may be as simple as a bad index. If so, you might fix it with:
Tools | Database Utilities | Compact/Repair
If that doesn't solve the problem, it may be just one record in one table
that has gone bad, and you may be able to rescue all the others. Follow the
steps for the first 3 symptoms in this article:
Recovering from Corruption
at:
http://members.iinet.net.au/~allenbrowne/ser-47.html
