Does anybody have any idea as to why this may be the case? The thing works perfectly for every system I own, with the exception being my XBox, which it fails to turn on two out of every three times I try. I have tried playing with the device delays (power-up, inter-device, inter-button), but none have helped my luck. Is there any explanation for this?

Try using the default delay settings again for the Xbox360 and see if the Xbox360 will work correctly. The only other setting you might want to try is setting the number of repeats.

I just ran into this problem last week while setting up a URC200 for a realative. They have an XBox360, and I was programming a macro for this as an activity. I used my MX850 to obtain the descrete "on" and "off" and then taught them to the URC200. I was only getting the XBox to turn on about 50% of the time. I told them that they might have to press "P-on" if the XBox didn't turn on when they selected that activity (wasn't proud of that:rolleyes:). Then I read the other day that a possible fix is to send another command for the XBox first, and then the "power on". I'm thinking that it might be to "wake up" the XBox (purely speculation). I haven't had the time to go back to the house to try this, but it might be worth a shot for you. If you try it and it works, let me know.