Problem:
When the command line gfix is run it gives the error: "Your user name
and password are not defined.  Ask your database administrator to 
setup an InterBase login."

Solution:
You need to specify a user password so that InterBase can validate 
the user who is trying to gfix the database.

This can be accomplished in 2 different ways:

1) specify user/password on the command line.  The user/password 
     arguments must come AFTER the other gfix arguments.  ie:

          gfix -v -f -user "SYSDBA" -password "masterkey" employee.gdb

2) use the environment variables ISC_USER, ISC_PASSWORD. 
     If these are set gfix will use them to validate the user against the 
     security database.