I typically leave my mac pro turned on around the clock and everything is hooked up to an APS battery backup system. Over the last several months I've had a problem where I will go to the computer and it has shut down and the APS power is off. I then turn the APS back on and when I hit the power button on the computer it trips the APS off again. I have to do this several times and sometimes unplug/replug the APS before I can get it to hold power and allow the computer to turn on. Any ideas what may be causing this?