This is too funny, as it just happened to me yesterday! Hah! I was actually at the dentist's office and he asked if the thing could take memory sticks. I said sure, let's give it a whirl. Anywho, we stuck in the MS ProDuo and it went it too far. Needless to say, the dentist was not happy that my Reader just ate his camera's memory card! Fortunately, being a dentist, he was able to get the lil' bugger out. That's when I came to the realization that it takes standard MS & MS Pro, not the MS Pro Duo w/o adapter (of course almost all of these come with adapters included!).
Doh! Cool coincidence that this happened to someone else at the same time (probably more of you guys/gals out there that did this, but you aren't fessing up just yet
)