My camry door locks behave randomly, when the car stops and I try to
open the door, the lock will lock and unlock. Also some times it
violently locks/unlocks automatically making a terrible sound.(at a
frequency of 2-3 lock/unlocks per sec.)

There is a old alarm system in the car, it was there when I bought it
used. I don't know if it is the alarm system's problem or Camry's
problem.

Does anybody have similar problem, or where should I take it to fix it?

Any inputs will be appreciated.

Thanks,

Rahul