When importing images from various cards and/or cameras, I get broken images that I can't open or develop any further. Later, when developing some good images, a few more get "broken" like this. Any ideas on what to do?? Thanks!
This is file corruption. It's (almost always) caused by a hardware problem. Memory cards are a frequent suspect, but you've said it happens with various cards and cameras. Card reader or camera cable would be the next port of call. It can also be things like the hard drive dying, a problem with the usb port, damaged RAM, etc.
it happened to me too and the problems was one of the USB ports on my computer. I was using USB 3 UDMA Hi Speed card reader and some of the ports in the front of my computer could not handle the speed properly so I got intermittent damaged files.
Try and change the port you are connecting the card reader to. Also if you import the same images several times you will probably see that different images get corrupted which will eliminate the memory card as an issue.