I agree with both Brian H. and AccessHA
that electronic device(s) could be either
creating noise or absorbing the X10
signal. However, adding a phase coupler
will solve 90% of all X10 communication
problems so anyone who is serious about
using X10 should have one. In my mind,
there is no point even trying to debug the
problem if you don’t have some sort of
phase coupler. If you are having problems
and you do have a phase coupler I wrote a
tutorial on powerline noise at:
http://www.x10.webhop.org/Powerline_Noise_an d_Noise_Filters.htm