LifeinAsia - 6:25 pm on Nov 8, 2012 (gmt 0)
More than a few times!
As g1smd said, always try out on a non-production server first.
And even then, make sure you have a recent backup (and a backup plan) before implementing on a production server. I've had a few times where something went quite well in Development, but caused a meltdown in production, despite being nearly identical environments.