In my office we have a number of decrepit "all-in-one" desktop machines, where the monitor is melded in to the base unit.
With age they are all slowly developing some sort of internal hardware issue whereby the built in screen stops working. Our IT dept doesn't do hardware fixes, they are well out of warranty and it's extortionately expensive to get them repaired by the manufacturer - so we purchase new machines to replace them. This is great in many ways, because frankly they all needed replacing many years ago, but the problem behind this is that while we wait for the replacement computers, we don't have enough working machines for all of our users at peak times.
As a temporary work around, it would be useful to hook up an external screen to these breakdowns. But, connecting an "external" monitor doesn't directly help - it works while booting, but once Windows (XP SP3) takes over, the second monitor stops recieving signal. Obviously, with no working screen I can't access any of the options to enable the screen directly and there are not magic functions keys on desktops (that I know of). And I can't connect monitors to the machines before they breaksdown; we've only a few spare monitors and barely enough space on the desks for them.
So, on a desktop running Win XP SP3, is it possible to blindly activate a second monitor?