Yes, I tried killing all of the apps. The last app I remember running before I picked it up again was Navigon, version 2.0. And when I noticed the problem I was in Goodreader looking at a PDF. It was in Goodreader that I noticed the problem. I have tried several reboots (power/home button reboots) and nothing seems to be working. Could whatever device (gyro?) that allows the device to detest it's orientation be broken, as in physically broken? Of course, there is no visual damage to the iPad.