I am running OS X Mountain Lion, for starters. I am using LR3 and no updates are needed. I am using DNG coverter 18.104.22.1684
I use a Nikon D800 and since I can not import my raw NEF files into LR3 b/c of the camera not being on LR's list (and no, I can't upgrade to LR4 right now), I've been using the dng converter.
Today, I put my camera into the Mac's built in slot on the side and tried to convert the files as I have been since I got this camera two months ago. This time, there are 900 images on the card, it converted about 200 and with the rest is says there was an error converting the files.
The images are there, I can see the 'greyed out' file names and I can see the images in PS Bridge. I really want to get them into LR, though b/c that's where I do most of my editing...
Thanks in advance!
The first thing I would try would be to use a card reader instead of trying to download/convert from your camera. If the card reader by itself doesn't solve the problem then I would try downloading the images to the hard drive first, and then convert.