power locks randomly unlocking

I have a 1998 Taurus. My power locks will unlock themselves randomly. I went to AutoZone and asked for a new power lock box thing (i'm sorry i don't remember the exact terminology) that goes into the circut box but the guy there said that i needed to take it to the dealer because what was the problem was under my driver's seat and was electrical. please tell me what i can do to cheaply fix this problem.

I experienced the same erratic action with the locks and the dome light on a 98 Taurus SE. They among other features are controlled by the GEM module.

The Alt and battery failed soon afterward and when they were replaced the problem went away.