Lightroom doesnt respond last version installed 6.3.1

I've dowloaded the last version of lightroom 1-2 month ago and it keep crashing even when i'm just scrolling down through my library, also when i want to import new Raw pictures from my sony a7s3 i'cant see the picture i just see a bunch of grey square with a tick box, i used to be able to see what picture i was gonna import .......