The resolution at which you send the files from Lightroom to PS is irrelevant, don't worry. As long as you're entering the correct size and resolution in PS's crop tool, that's all that matters.
Have you tried ...
Connecting the card to another computer to see if it reads it there?
A different card reader?
Another card in this reader to see if it reads ok?
Ok, that's a bit better. Still not great, but out of the danger zone at least.
I encourage you to run Glary on both computers when you get a chance, and maybe Scanner too. When you have time.