Modules Turn On or Off by Themselves
Why do some modules sometimes turn on and off by themselves?
Certain devices in your house can cause electrical interference. Devices such as baby monitors, wireless intercom systems, or anything that transmits signals over the house wiring might interfere with X10 codes. Televisions and computers can also transmit noise, even if turned off. This interference can stop X10 signals from getting to the right module(s), causing intermittent control.
In some cases, it is possible for this noise to change a transmitted code into a different one, which might cause the wrong module to turn on or off. The easiest way to determine whether or not a household device is causing interference is to unplug it entirely. If this fixes the problem you may consider plugging the offending appliance into an X10 Noise Filter XPPF found here.