Chris,

The house is about 2500 ft (two storey excluding basement). Basement is not finish so there are only several wall receptacles and some ceiling lamps.

Is the testing device simple to use? Like plugging in to a wall receptacle and that's it? Or I need to do something specific? I will seriously considering loaning it from you if you wouldn't mind. But I do want to wait a little longer and see if I can isolate the problem.

No, I do not have any amplifier installed in the house for X10. Maybe that is something I need to do. I will need to hire an electrician to do it though since I'm just an no-brainer in front of a circuit breaker box. I'm also considering putting a whole house surge since I now have invested some money on X10, I don't want them to get toasted by a lightning.

Thanks Chris for your offer. I'll let you know if I really need it.

Simon