Does he have any surge supressors in that room or through out the house? These can eat up the X-10 signal. Installing a Phase Coupler would be a wonderful idea even if he wasn't having problems, yet. It is a way you to improve the X-10 operation and make it more dependable. More that likely, all homes will need a phase coupler. The best soultion is to install the amplified version but the $$$$$ of it will decide that.

Chris