Car Alarms: Car Alarm is set off for no reason, valet mode, gmc suburban

Question
I have a 1991 GMC Suburban with a non factory installed Prestige burglar alarm.  It has worked perfectly until last week when the car battery and starter were replaced.  Now once it's armed, it periodically goes off for no reason.  

Any thoughts?

Answer
Seems the system is reset, and needs
to be done again.

Probably when, or if it lost power.

Right, Ok, try this.
Put the key in the ignition, and turn forward
all the way just before cranking. Then within
5 seconds, press and hold in the valet/overide
button, found under the dash area, usually to the left
of the leg, drilled into a plactic panel.
Might even be part of an on glass antenna
in the widshield if it's a remote starter,
until the installed LED (the blinking light)
in your dash area goes off, and the siren chirps twice.
(Your valet switch might be the toggle (on/off) type.
in this case, key on, flip switch in oposite direction,
key off.)

This should reset the alarm and allow you to
go on your way.

Just Repeat these steps to place it
back to valet mode.

That should do it.

Good luck.

ALARMTEK