Car Alarms: Alarm malfunction, chevy venture, factory oem

Question
I have a 2003 Chevy Venture which I bought used few weeks ago. Everything is Ok except that I noticed recently, the alarm goes off if the door is opened when unlocked with the key as opposed to  the unlocking  it with the remote - in which case it is Ok.
I do not remember it was doing this at the beginning.
How can I get rid of the problem?
Thanks

Answer
Here's the thing, this system depends on the door locks
to be unlocked by remote, or by putting the key in the drivers door,
turn left first, then right to turn off the
factory alarm.

It's integral to the arming and disarming of the
factory/oem system. They work together by design so
there is no simple way to seperate them.

Simply use the remote as intended. The system is
doing it's job.

Have a good evening.

ALARMTEK