Is power off the only code you have issues with? Odd, but I have seen odder. We have had issues with Sony projectors and RS232. Oddly (there's that word again) enough, with the power on command not working reliably. Upon looking at the driver (C4), I noticed that the ON macro issued the command twice. Not sure why. I switched the problem ones to IR and never looked back.

Sony says it is the length of the cable run. We use CAT5e with DB9->RJ45 adapters and sometimes spliced to 3.5mm stereo ends depending on the controller being used. I think they said we should not be running RS232 longer than 15-20'? The funny thing is that we have ones that are closer to 50' that we have not had an issue with. And we have had ones that are closer to 20-25' with issues. So I do not think it is strictly a cable length issue.

I wish they would all just put ethernet ports and give us IP control. It is 2015 for crying out loud! I can IP control a damn refrigerator!