What happens is that the monitor that comes with this computer is a versatile monitor, and is equipped with both an old-style (VGA) connector, as well as a new-style (DVI) connector, so that no matter which type of connector your computer has, this monitor can connect to it without having to use an adapter. The computer is similarly versatile, having both a VGA and a DVI output, so that no matter which type your computer has, you can hook it directly to the computer without an adapter. It also allows you to use the VGA connector for one monitor, and the DVI connector for a second monitor.
These customers were doing what most computer users do: they unpack the computer, and stick all the cables into the ports that match up. In this case, they end up with 2 cables connecting their monitors to their computers, making the computer think they had a dual-monitor setup. It's not a big deal at first, because the main display is the one that is displayed on the only monitor. But when the computer goes to sleep and then is awakened (or sometimes when it starts up), it somehow sends the signal for the second monitor to the only monitor, thus showing a screen with a background, but no icons, task bar, or start button.
The fix is simple: don't use both cables at the same time! :)
