Hey IVB:
I've had this issue with two different GE Crystal Micro contact sensors - luckily each of them has only had the problem once. The first time, we were laying in bed at 5AM and heard a voice chime ("front bedroom window") immediately followed by the alarm of course. This is on the complete opposite side of the house from where we sleep, and needless to say I thought it was for real, so I had a gun in my hand and was running that way within 10 seconds (but hey, I live in Texas). I got to the front bedroom and all was well with the window. I was able to immediately silence/acknowledge/re-arm with my keyfob, so the violation of the window was only transient. I put it down to some peculiar occurence of interference with the crystal frequency and went on with my life, albeit with a tanking WAF due to the scare.
About 2 weeks later, I'm sitting in my living room (which is open to the kitchen) with the Elk disarmed, and I hear a chime for the kitchen window - same deal - no actual violation could have occurred. THANK GOD the wife was shopping at the time.....I got a little worried when this happened, but neither of them has acted up since.
To test range, I took both of the sensors twice as far away as they originally were, and walk-tested them in mid-air (with my wife's help). I could not get either of them to lose signal with the receiver until I was more than 500 feet away, and that was through A LOT of obstructions both times, so I don't think it's a range issue. Both of these sensors are in sight of the street in front of my house, which is fairly busy. For these reasons, I suspect that something is causing a passing inteference with the transmitters, although that SHOULD cause a transmitter missing trouble, and not a violation.
No false alarms while away from the house yet though, (knock on my wooden head) and I admit that after the second time this happened, I did get a little worried about false away alarms, which would cause my wife's phone and work email to receive text messages, thoroughly freaking her out and making her question our investment. The security side of my Elk is COMPLETELY wireless and relies entirely on the M1XRF, so this is particulary pertinent to me......
I asked Jim at Automated Outlet if he ever experienced this issue when he was beta-testing the receiver for Spanky prior to its release - he said he never did have this happen. I asked Martin too, but if I remember correctly, he didn't beta test this particular Elk module. Anyway, I believe there is something very specific happening here, and I hope whatever it is stays FAR away from my house from now on......