Im new here this will be my first post. Probably a stupid question because you prolly already done this, but have you tried to reboot with the remote? press ctrl+alt+backspace at the same time. When I get that error on mine, that is the only way I have been able to get it working again. Also the OS is on the ethernet board I believe and that is why changing the motherboard did you no good, although thats about all I can do for you also, as I have yet to attempt to ,"fix" "flash" "reinstall" however you want to say it, mine yet since the reboot with the remote seems to fix it so far. Plus it happens very little to mine as of now. Hope some of that info might help.