Optima Rf Wire Free Alarm - Door Contact Issues?

my optima rf wire free alarm system has a mind of its own. The door contact on the front door is the issue, when the alarm is disarmed and we are in the house the panel starts to beep and zone 5's led comes on solid. When i try to restart it clears then alarms again, but the main alarm bell doesnt go off. I have checked the position and replaced the battery and it still alarms. any ideas