This may be hard to believe, but there was a time when Jim Carrey was known as one of the most popular actors on the planet. Remember Ace Ventura, anyone?

But the funny man hasn't had a box office success in years. Which was fine when he was seemingly busy and content with Jenny McCarthy.

Ever since that pair broke-up, though, Carrey has unleashed a stream of Tweets that has fans concerned: might the actor have fallen off the deep end? For example, he recently referenced his character in The Truman Show and wrote:

"I have freed Truman at long last! I am grateful for my avatar's many yrs of dedicated service, but no one has ever won the Tour De France while back peddling... so I killed him."

Well, okay then. At least Carrey isn't still placing some blame on Elin Woods for her husband's infidelity.

Carrey acknowledges that "some folks out there are worried that I stay up too late," but he insists: "This is no breakdown! It's a breakthrough! And if you'll just loosen these straps, I'll show you the difference!"

Sorry, Jim, but we're not convinced.