RWblah, any button with the exception of Play/Pause should dismiss the screensaver. If you're seeing something different, something is wrong. Many of the Roku screensavers have little advertisements floating by for various apps. Pressing Play/Pause confirms that you want to install that app - note the Play/Pause symbol on the ad. Press any other button to dismiss the screensaver and then press Play/Pause to continue.
There's also a built in limit to how long you can even remain in an app if not actively streaming. I believe it's two hours, so you can't pause forever, but that has nothing to do with any screensaver.
