Maybe once a month I find this message in the log file:

C093 (Server) Thu Oct 19 08:15:48 2006
Database: E:\DATABASE\CBSFUNGI.FDB
internal gds software consistency check (invalid SEND request (167))

After that all accesses to the database fail, because the database
file 'is locked by another process'. The remedy is to stop and start
the Guardian. There is no sign of damage to the database, backup and
restore function without any problems.

The problem always occurs when the server is very busy, but not
necessarily with the databse file that cannot be accessed afterwards.
This morning it happened during a restore of the database to a new
file, sometimes it happens at night during backup and compress jobs,
when people are accessing the db over the internet.

The server is an XP server running (still) Fb 1.5.2

Any ideas?
Thanks,
Gerrit Stegehuis