internal gds software consistency check

 i am getting the following error in the server log for IB6:
"internal gds software consistency check (pointer page vanished from
relation list in locate_space (254))"

when this happens, clients cannot access the database through our Delphi
4 app server. on the client workstations the "general SQL error.
Database conection lost" message appears. i have to get everyone to kill
their client software. then i kill the app server .exe  and restart it
(only takes a second) and we are up and running. this may happen only
1 -2 times per week. it can also happen when there is no client
connection to the database (which is very confusing to me). is this
hardware related? thank you for any input.