Odd Issue with Driverack PA2 - No Sound

Ever since I have had my Driverack PA2, it is wired into a rack with a Furman PDU and a line mixer and wireless mic system. It runs my karaoke setup and plugs into my laptop. I flip the switch and everything powers on at once. Sometimes I have sound, sometimes I do not. There is no rhyme or reason to it. I sometimes have to reboot my laptop in order to get sound or I have to power off the entire rack and back on again and sometimes I will get sound that way. It is like the PA2 doesn't detect an audio source or something. My friend has one of these in an almost identical setup but he doesn't have a switch that turns everything on a once. He turns things on individually. Is there anything about powering everything on at once that would cause this intermittent sound issue?
Once I have sound, I never lose it and things are fine so it has to be something with the boot up of the device.