I have done the OldParameterOrdering procedure, but it seems not to
solve the problem. I have re-analized the code, where the sequence
of operations is the following:
TIB_Query.Open
assign SQL
TIBQuery.Active := true
GoTop function
GoTop function
StartTransaction
TIBQuery.Active := true
TIBQuery.First
TIBQuery.RecordCount
Commit Transaction
TIBQuery.First

I did replace the GoTop call, keeping just the last TIBQuery.First,
and it seems to work. I guess that the doubt here is if by making
two .Active:=True to the same object would cause Firebird to crash,
and not just leave the problem to the application keeping Firebird
running?
Thanks,
Horacio C.