RalfG said:
Buggy display drivers excluded, Windows won't normally jump to the
secondary display on its own. I've seen it happen the odd time during a
messy driver update, but that was rare. It's only a matter of putting a
check mark in a box to switch the secondary display to the primary though.
I would have agreed with you - 6 months ago. But it happened to me when
Windows Media Player just displayed a black picture after a complete Windows
rebuild. It turned out that the picture was on the (non existent up to
that point) secondary monitor. I had to connect one up just to get the
picture back. It has happened to a friend of mine, and it happened to a
subscriber to comp.sys.laptops a couple of months ago.
I suspect the display positions are resetting to default on this system
because Windows is switching back to single monitor mode in between dual
monitor sessions. Depending on what options are available in the advanced
display settings for your adpater you might be able to bypass
auto-detection and force the secondary display to remain on. OTOH, with
power consumption being a consideration for laptops that might not be
desireable.
The position switches back to the default location if you disable dual head
operation by unchecking the 'Extend my Windows Desktop onto this monitor',
or if you physically disconnect the monitor, in which case it auto reverts
to single monitor operation. Only if you just switch the secondary monitor
off, without disconnecting it, is the dual status remembered. It seems that
the graphics card can 'see' that the video lines are still terminated and
thus assumes the monitor is still there. This auto detection is a feature
of the graphics card and (presumably) its drivers and not windows. I am not
aware of a graphics card that doesn't auto detect in this manner, but that
doesn't mean that there isn't one. The only down side is that the mouse
cursor (and indeed windows) can be lost onto the secondary monitor's desktop
space.