Chigley wrote on Apr 25^th, 2012 at 7:33pm:

I've twice had a power black out after running with battery and ground power only, AC and DC switches to Batt and Grd Pwr. I've then switched to looking at info from the windows drop down menu ie payload and fuel settings or checking arrival destination height values, returned to FSX only to find that the power has blacked out. Grd pwr indications were out, AC and DC selector switches had returned to Stby Pwr and the Battery switch had turned Off with the guard open.

In the quote I've highlighted the real reason of the blockout: fsx menu use = paused flight sometimes causes the sys.gau glitch.
Anyone to confirm this?