Jim L.,
First, make sure that your lamp module is
plugged into the same PHASE-LEG as your
Computer Module, and test again.
X10 does not repeat signals, so if at the
time of your event, if there is noise or
the two phase-leg's of your home are not
joined by a device that uses 240v., then
you will not be able to communicate with
that device.
Which controller are you using for your
computer (Firecracker or CM11..etc.)?
Some controllers do not retain
memory/functionality when the computer is
off, and don't work without
the "communications bridge" present.
If the problem is Phase-Leg related, you
can either install a capacitor across a
240v breaker, or purchase phase coupling
device. Unfortunetely, this does not always
work. Sometimes a repeater is necessary to
solve these issues, but usually we start
from least expensive solutions, and go from
there.
-John Martoccio