Hi flakes, welcome to the forum!
Can you give us a bit more information? It would be useful to know:
Mac or Windows?
LR version number?
Basic machine specs?
(Most people put those details in their signature to save typing them over and over again. You can find the signature settings under Control Panel on the menu bar above.)
Camera?
Where you're seeing the grey - just in the import dialog or in the Library module too?
At first guess, I'd say your graphics card driver needs updating, so that's probably the first thing to try.