...just right-click on the Shorthand icon in the tray (is that what that area is called?), select Close Shorthand, but don't click OK when the application window pops up. My enter key starts working again while this confirmation window is open.
For me, it doesn't stop working completely, just when I try to do a carriage return in Gmail, on my blog, or in instant messaging. So once I've finished doing whatever it is that's requiring a carriage return, I just hit cancel in that confirmation window.