I was experiencing similar problem with 3 dimmer switches that formerly worked perfectly "degrading" to working fine when manually manipulated but not responding to remote commands. Circuit breakers on-off experiments and then specific appliance plugging/unplugging led me to the culprit: I'd gotten a Sirius table-top radio (TTR1) last week. Just a small, simple plug-in device (not a grounded plug), but it must be an awesome signal sucker. It's an internet-based box rather than having its own Sirius antenna, and I have it set to access my network wirelessly. At first I thought it might be the wireless broadcast/reception that was playing havoc, but since it seems to cause the problem as soon as it's plugged in, even if not yet powered on, I suspect it's pure signal-sucking. I've experimented a bit with moving it around, and it seems to have its deleterious effect based somewhat on the proximate locale relating to these affected wall switches, which I'm guessing also indicates they're already my weakest signal receivers. They are indeed also closest to my office, which has no X10 devices but 2 unfiltered computers and assorted corresponding peripherals. With the radio unplugged, all these switches work fine, with the exception that the one closest to the office will turn on but not off or dim. Next I'll try turning off the computer components one by one to see if that last function gets restored. Of course I had all the computers off when I originally set this stuff up and verified all switches worked, because I was turning circuit breakers on and off during installation, and that included the office circuit.