Screen starts to change between apps with no one touching it?

I have an iPad 2 - and recently I have noticed that I will be on an app and all is working well, and then the screen starts to move with out being touched. The iPad will move out of the application, back to home, then into another application, scroll and then start a new application. There seems to be no real rhyme or reason to it. Then I turn it off holding the Start and Home button - sometimes that fixes it, sometimes it doesn't.

Thoughts?