First thing to do is turn off the GPU option in the LR Preferences on the Performance tab. If that doesn't help then try a different, New, memory card. They do go bad over time and use
Could be what you have is some type of hardware problem. Could be the card, card reader or cable used to connect the reader or camera to the computer.
LR never touches the original files so what you are seeing is in the displaying of the images. If you go to the develop module do they look like your screen shot?
Thanks a lot for the pointers. I will experiment with the GPU option.
I don't think this is the cards - I have the same thing with three different cards. I've ordered a new card reader as well to see if this helps.
This is a corrupted file, caused by some hardware malfunction somewhere. It could be camera card, or transfer to computer, or hard disk or memory. You need to see if you can isolate the cause by trying different hardware.