Richard,

> 4. Installed Firebird v1.0.5 in the same place as Firebird v1.0.3
> was, due to Client hard-coded references
>
> 5. Tried running our gateway app that uses Firebird, but comes up
> with error "there is no user login account. Please ask your
> Administrator for Firebird"

You're sure the message wasn't:
"Your user name and password are not defined. Ask your database
administrator to set up a Firebird login." ???

FB 1.03 uses isc4.gdb as user database,
Firebird 1.5 uses security.fdb.

So you have to add/modify your users once again.

You can use gsec for adding/modifying users.

Luc.