Actually, recently I also have this problem whenever I've become disconnected from the internet; the exit button on the browser page disappears when it doesn't load the full page. Connecting back to the internet and loading the page restores it. When it's not there, I find 99/100 times the oculus home button is also non-responsive. As a Link user I have to unplug, which pulls me out of the Rift/Link software environment completely.
