Every now and then my computer monitor flips upside down. I don't know how but occasionally my "alt" key seems to get stuck, then when I go to my browsers address search bar to hit CTRL-A and then arrow down, I end up with the magic CTRL-ALT-Down arrow combo which under windows with Intel graphics cards is a shortcut for flipping your screen. Now while I see the potential for great office pranks I can't see why on a desktop machine this would be enabled by default. Luckily there are a few steps you can take to prevent this.
First find the icon in the right side of your task bar for the Intel driver. You can right-click on it and navigate to the menu to turn off hot keys. Alternately you can right-click on your desktop and select Graphic Options... from the context menu. You can bring up the main dialog and turn off both the hot keys and disable rotation. When I did this and then tried to reverse the process the default hot keys for flipping my screen were gone. Whew, now it's a little more work for those office pranksters (my wife) to pick on me.