Yes, I should have known better.

I had my X51v in my fairly new Magnum case on my beltclip while brushing the snow off my car to go to work. Next thing I knew, the PDA had fallen off the beltclip and into the snow. After searching frantically in the drifts, I found it. It was so slippery than I ended up dropping it twice before getting it back to the house. But I got it all dried off and it still works fine.
Those Magnum cases are really nice, but you have to check the tightness on that flimsy screw every once in a while to make sure it's still tight. I wish somebody could come up with a better design for a secure beltclip.