alram arming it's self after 2 minutes

[eleuki]

Just recently got a 94 Jetta and the problem is after
disarming the alram.. 2minutes later (roughly) the
alarm will arm it's self.
I have to reach through the window and lock and unlock from
the outside to disengage it.

is there a way to make it work properly? or is this a common
problem due to something else?

Thanks