Kelly,
I once had a switch that was set to house code “A” unit number “1” to control my kitchen lights. It worked fine for about a week then it freaked out. It no longer would work on unit number “1” but instead chose “9” to control it. No changes were made to anything. Now 1 and 9 are close in that they are 180 from each other. Don’t know if that made any difference but… Anyway, I ended up having to replace the switch and all is fine. In your case, having different house codes and unit numbers, I don’t know if it is possible. (This is X-10 so anything is possible). When you say “(with a repeater set to “A”)” what exactly are you referring to? Also, what X-10 switches are you using? Some have the ability to transmit X-10 commands as well as receive? Has this always been a problem or just a new one?

Chris Couture