You could certainly simplify it.

First off....you are turning on your xbox twice.

The section from if(system power, off) could be greatly simplified. Not sure if this will help your problem but it will make it a lot easier to read and maintain

if(system power, false)
delay 3.0
var system power =true
alias TV-HDMI2
delay 0.1
ALIAS receiver-dvd
if(system mem, false)
delay 0.1
alias audio 3-left
jump media center

I am fairly certain that is functionally equivalent to what you have and a lot simpler. The indentations indicate what should go inside the if.