>
> Check this
> AV in engine when preparing query against dropping table
> http://tracker.firebirdsql.org/browse/CORE-3557
>

Hello Claudio and thanks for your comments. I think the access violation that you mentioned doesn't explain our case. We haven't noticed any crash or access violation but the corruption of our database. If we try to take a backup of the database, it fails with the following error:

gbak: ERROR:internal gds software consistency check (missing pointer page in DPM_data_pages (243), file: dpm.cpp line: 677)
gbak: ERROR:gds_$compile_request failed
gbak:Exiting before completion due to errors
gbak: ERROR:internal gds software consistency check (can't continue after bugcheck)

We are using Firebird 2.1.4 and previously we used 2.1.2.