WHEN PROFESSORS LOSE IT: An interesting article from Inside Higher Education.
The tenure process is, indeed, tough. I don't know anyone who's lost it as a result, but most people going through it are a bit stressed. It's hard not to be, when you're being judged -- according to not-entirely-clear criteria -- on pretty much your whole professional self, and a good deal of your personal self, too. The prize is a lifetime of intellectual freedom, though, at least in theory.
At my school we have post-tenure review (I just got mine for this year -- I 'exceed expectations' in all categories, and the blog got a favorable mention), and I think there's more attention, and peer pressure, for post-tenure performance than there used to be. But the all-or-nothing nature of tenure evaluations is stressful.
UPDATE: In a related post, Daniel Drezner says that David Horowitz understands the academy. In a Stanley Fish sort of way . . .