Yes, the tooth fairy is a good next investigation...
Until then, thank you for your responses. I very much appreciate your time to assist me.
I did speak with X10 support who said similar things. One thing they did mention was to also change the number code, which I did not do. I will try this as well.
For more background, I live in Toronto, Ontario and yes, we do have a Smart Meter installed. This meter was installed before we upgraded all the wiring in the house. I'm not aware of how this could affect the switches but this could be a factor - however, this was not a factor before beginning to use the Insteon Hub.
Also, I had planned on installing AHP, but hadn't before trying the Insteon Hub. So, I've only been using the switches manually up until this point. I was awaiting stock of the CM15a from X10 and then purchasing that and the newest version of AHP.
X10 support also suggested resetting the switches by powering off each breaker for 10 minutes to possibly reset them. I had thought that these switches were 'dumb' in that they just listened on the line for instructions and then followed them, without storing any info on the switch itself, but support said that this was also possible.
I'm going to power off the breakers on each switch for 10minutes to attempt to reset them and see what happens.
Failing that, support also suggested removing the switches that are problematic and swapping them with known 'good' switches to see if there could be anything with the powerline in the location, rather than the switch. This sounds like a good investigation as well.
Thank you for your info on noise and the probability of noise turning on switches. This is very helpful as I continue to investigate. Also, we do not experience any flickering or noticeable spikes in power. We haven't had any issues before.
We do have a baby monitor, which we have unplugged since this began, just to be sure that this wasn't a cause. We've also unplugged the modem and most electronics as a precaution.
I wonder if the fact that there is now nothing controlling these switches cause them to act erratically.
I wonder if the establishment of a working AHP system with a CM15a would try and 'take hold' of signals and return order to the system.
With this additional background information, I would still value any other thoughts that you might have to try and address this problem.
Many Thanks!