#2. "RE: D5100 and Lexar Platinum 11 SDHC memory card" In response to In response to 1
Thank you for your advice - it was really helpful. I do have a card reader. I bought it so that I could update the camera's firmware but I haven't worked out how to do that yet (another story for another day!!)
I just put the memory card into the card reader and plugged it into the USB drive on my pc. Oddly, it shows only half the recorded images that are on the card. I checked the "properties" of the card and there is at least 50% available so I'm not sure what's going on.
The corrupted photos aren't really worth recovering but I don't want any important/precious images getting the "chop". It seems that the shop from which I bought the camera and memory card will replace the card but I'd hate to have problems again with the same brand of card.