(This problem started months before the one I posted as "Problem by HouseCode? It used to work!" in the Modules and Switches area.)
Have a PS561 (X10 PowerHouse "Personal Security Console with Voice Dialer"). For some time Zone 4 (Dining Room Door) has been slowly (~1 Hz) flashing, which seems to indicate the module has not 'checked in' with the base in over four hours. If the door is open and the alarm is set rapid dinging; if the door is closed can set the alarm normally, which seems to indicate there is communication. The sensor module has been replaced/swapped out -- same results. The module has been moved: along the floor and on a table. Sometimes will been 'seen' and the slow flashing stops for a while (week or two). ...Lately have noted if the slow flashing stops if the door is open the LED will be on constant (door open indication), if the door is closed the LED will be off (door closed). Open or close and the console will immediately go back to the slow flashing.
Have 'rebooted' the base console (PS561) ==> unplugged from AC and removed the battery. This requires reinstalling the various devices. Hasn't corrected the slow blink supervisory error. And yes, it does give the five 'dings' error periodically. Distance between the door sensor and base console is about 20 feet; the signal does travel through walls with ductwork and electrical/electronic.
Am thinking about getting the V572; wondering if this would help for the potential communications problem (though that brings up the potential of a weakened security system if the power fails).