I am trying a surge protector to see if that stops the intermittent actuation. It seems that the intermittent operation often occurs when another appliance is turned off or on (these other appliances are not connected in any way to the X-10 system).

I went into the outlet box and found that the ground was not properly connected, but the X-10 module is only a 2 prong device. I corrected the ground problem, but it didn't cure the situation. I'll let you know how the surge protector works.