Barry,

c> C:\Program Files\Firebird_1_5\bin>gbak -b -u sysdba -password
c> masterkey d:\bgt\cem5_test\cem5.gdb d:\bgt\cem5_test\fire1.fdb
c> gbak: ERROR: unavailable database
c> gbak: Exiting before completion due to errors

local connections aren't available under terminal services.
Prepend "localhost:" to the gdb parameter you pass to gbak.

Ciao
--
Nando Dessena
mailto:nandod@...