I love the DisplayLink USB display adapters that let my piddling little tablet PC drive 4 1920x1200 external monitors.
However, many, umm, irregularities happen with Windows 7 support and/or the display or device drivers.
Earlier today, and for weeks if not months, I have been able ti have 5 displays - my laptop/tablet PC's built in LCD, and my 4 external displays.
However, I went into hibernation while travelling from home to work (where I did not use the PC) and back to home again.
And when I woke up, I cannot get my laptop built in display to work, when the external displays are plugged. Sure, it works when they are not plugged in; but when they are plugged in, the laptop built in display gets "blackened" in the Orientation box.
Just yet another Windows 7 strangeness.