Please go to the Preferences of the Lightroom and under the preset tab un check the option which says "Apply Auto Tone"
Then re-import the images.
"Could not be read" means a write permissions problem with the destination folder - fix that in the OS.
Grey thumbnails indicate a corrupt monitor profile. Reprofile your monitor and see how things look, or (as a test) change the monitor profile to sRGB.
I used a different card and that worked, so then went back to card I was having problems with and that worked. Must have been jammed somehow