I've been doing CrossFit for six years, this past December during a 'holiday' WOD I got nailed by acute rhabdo in my right arm.
It took many months of rehab and different body work techniques to get things back to normal. Very, very, painful process.
Honestly, the workout wasn't out of whack with a tougher than normal day. It was for me, however something that put me out of commission for five months.