Problem with High Sierra, iMac PS CC 2019 freeze +crash

I've never had this problem before, but maybe you have?
I have a new to me d300 and brand new flash drive in it,
took a bunch of exposures, and dragged/dropped them from a flash drive onto the thumbdrive and i am using
( plugged into the back of the computer ) ... I loaded PS CC2019 and everything was fine until it wasn't.
All of a sudden working on photo 12 or 13 and PS does the FREEZE and CRASH --- I've had to go back to a pre-crash clone back up
( which i am on as I type this ) but I haven't loaded PS again or tried to re-work on the stack of photos I worked on,

As mentioned, I'm working on the images on (a usb ) thumbdrive (images not on imac hard drive until I finish and save them ) .
Could this be my problem? Images ( IDK 33MB not huge )not on computer except through the olde maybe wonky usb port and Big Box Store thumbdrive?

Thanks for your sage advice !
John

I upload direct to my WIN 10 SSD from the removable camera drive

and never format a camera drive in the computer, I do that in camera, later

On WIN 10 I always eject the camera drive before physically removing it

My guru says that you need 16GB of RAM to run Lr and Ps. I have no image files in the on-board memory of my MacBook. They are on an external 1TB SSD and any work gets saved to the SSD. I take the memory card from the camera and immediately transfer to the external SSD.

So-- (or, maybe not "so") I haven't encountered that problem. I have enough other problems with Ps and Lr to keep me 'way down on the learning curve!

thank you both for your help !
i restored and reinstalled the OS
seems to have fixed my problem
now i just have to get hte courage
to try using PS...