I have an entire phase of my house that have stopped responding to any trasmitter; mini-controller or wireless.

Both will transmit on the other phase. I used the test from the tech papers on Bill's website to test the non-responding phase.

I verified that my LM and transmitter were working, then took them with an extension cord to the "bad" phase. I plugged the extension cord into an outlet and plugged both the transmitter and LM with a lamp into the extension cord. Nothing.

On the "good" phase this worked fine.

I have only made three changes to my X10 setup, then this started.

1)Installed a light switch on the "Good Phase". It receives signals for the transmitters on the good phase just fine. This switch was in a box with two other switches for other lights. On the old switch one wire went into the top post, where I used the blue wire on the X10 switch. Another wire "looped" around the bottom post and continued to the third switch. I hooked the X10 black wire to this wire.

2) Installed another light switch on the "good phase" in a box with three other switches for other lights. The old switch had one wire to the top post, and just like in #1 above, a wire that looped around the bottom post, unknown to where. There was a second wire from the bottom post to the bottom post of the next switch. I hooked the black X10 wire to both of those. Again I have control of this light at the switch, and via transmitters on the "good phase".

3) An alarm system with an X10 transformer to send X10 commands was installed on the bad phase.

As a note, I can Transmit X10 commands from SOME of the outlets on the bad phase to receivers on the good phase, but none of the receivers on the bad phase receive. I checked them all on the good phase, and they work.

All receivers worked prior to 1,2 and three above.

Could 1 or 2 be causing the problem? All of my potential noise, Home Theatre, computers, etc are on the good phase. Will noise typically stay within it's phase?

any ideas?

Noise is strongest on the ciruit of the noise producer. As you move farther away (electrically speaking) from the noise producer the noise level decreases. Just as X10 signals have problems getting from one phase to another so does noise.