bnt
I'm on my PC at work now and, by golly, you're right. There is an 'Intel Extreme Graphics 2' icon in Control Panel which brings up a tabbed display which includes Hot Key selection for the screen rotation feature.
Our Dell screens do rotate on their stands and I have seen people working (in Word, usually) with their screens rotated to portrait - can't see it being of much use on a laptop, though!
To disable the feature you can uncheck the 'Enable Hot Keys' box on the Hot Keys tab.
Gadget 