I have 2 clients with newish i5 ProDesk 600 machines, both with DisplayPort to VGA adapters from CDL to drive a second screen. Once or twice a week the LCD connected to the onboard VGA goes blank/black. If I VNC in, the 'display' on that screen is still operational, so I can save/close any work the user has on that screen. If the machine is rebooted or monitor is disconnected and reconnected (you hear Windows detecting this) and the screen lights up again. Drivers are up to date (as per the HP web site versions).
As these machines have dual DisplayPort plus the onboard VGA, I'm going to try driving both LCDs from the two DisplayPort connectors and abandon the onboard VGA.
Just wondering if anyone has seen similar behaviour or has any other relevant thoughts on possible causes/fixes.