We have around 40 Dell Optiplex 780 small form factor PCs. These have a standard VGA screen port, plus a Display Port on the main board for a second screen.
We configure these to run an extended desktop - ie Start button on left hand screen, with the screen just running across to the right hand one. However, quite a few of these lose their extended screen ability and either a) revert back to a single screen (RH screen going blank), or to a cloned display (RH screen an exact copy of the LH one).
Fixes tried so far:
Unplug and replug display port adaptor - works, but only temporarily.
replace display port adaptor - makes no difference.
update the bios - to version A04 - no change.
update the graphics drivers - no change.
Generally, it can be reset by changing Display Properties to tick the box to use the second screen (which has somehow become unticked).
One of the annoying things is that it isn't repeatable - it can occur while the same user is logged on, or more commonly, after a reboot. However, it doesn't happen every time. Running XP SP3. Screens are Dell 17" flat panels. PCs were supplied new a couple of months back, on our standard corporate build, and problem has been there from Day 1, but has grown since we rolled them out.
I can go to Dell with this issue, and possibly go for some mobo replacements, but just wondered if there's anything slightly less drastic to try first. Thanks...