Maybe but in this case if you can make an alteration by disconnecting the stereo it's unlikely to be a fuse issue, I called the guys at the place I had the alarm fitted, they say replace the batteries in the fob, again, I disagree... It has to be an interference issue of some sort... Guess I'm going to have to try to find a wiring installation diagram and check each wire....
As you said, odd problem, so expect a odd solution.
Did you measure the tension at the unit?
The stereo can function good on 10 volt where the alarm wil cut in range.
Most fall in tension are on the fuse-panel or contact-lock.
It is impossible to give a clear ready solution, because of little information how it is build up and not part of the standard on the Murena.