This happened once on my 'emergency' 16mb card (a Fuji one, no less), thankfully didn't lose any pics - did a format on the card and it's been fine since. I put it down to the cold & v.damp conditions I was in at the time.... plus the condensation factor of taking the card out as soon as I got home & putting it into the reader.... v.cold > v.hot conditions...condensation on the card? Dunno... Sorry about the pics, bud. (",)