You’re creating or editing a description for a SQL Agent Job and you want to add some lines or white pace to your text. If you press the <Enter> key expecting to go to the next line, SQL Agent job window disappears and the job is saved.
Fortunately, you do have a work-around, as provided by Andy Carter on the MS Connect site (see below). Simply use <Ctrl-Enter>.
As for a future fix, it was posted as a bug as far back as March of 2007 – and it appears Microsoft has no plans to change. You can reference the “Closed as Won’t Fix” posting here: