I have had to reset my Veritas 8C and have a new code, however, although the display is constant on 'unset', the alarm remains active. I'm currently unable to enter the zone without activating the alarm.

Oscar L, October 2007

You dont say how you recoded it - if you went back to factory settings then one zone is programmed as a personal attack button. If this zone is in truth a PIR then walking past it will trigger the alarm even if unset.
You would need to reprogramme that zone to attribute 3 - guard.

Alarm Engineer Bristol, November 2007