Welcome to the Lightroom Community. I'll need more info to help you figure this out. Please go to Lightroom Classic > Help > System Info > Copy & paste here.
Where do you keep your original images? Internal drive or an external drive? Test if the external drives are failing to stay up or crashing altogether.
In the meantime, try this:
Go to Lightroom > Preferences > Performance > Use Graphics Processor > Set it off if it is on Custom or Auto. If this shows you any differences, please check this article to troubleshoot further: https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html
Let me know how it goes. Thanks!