The Protector Plus resets after 4 mins I believe
which will make it trigger and sound the alarm when you come home and don't disarm before you enter!
Disarm before you enter and check to see which sensor triggered the alarm ( it should be illuminated)!
You can then see why that sensor sent the trigger signal (poor contacts maybe
)!
If you have AHP it will dispay which sensor triggered in the activity monitor and you can have it trigger a separate alert for you!
AHP must be configured to your unit so chances of a neighbours system activating your is slim!