Laptop or desktop computer?
When you are done using the computer, do you "shutdown" or "sleep"?
I am running a desktop. I generally close LR down but have the PC power settings set to go to sleep. But I just changed it to leave on full time in the event it was trying to sleep while an LR process was running.
I took my external drive holding catalog and photos and attached to my older HP laptop with I3 and 4 gig memory (I was running it on my desktop) and didn't have any problems. I only have USB 2.0 on the laptop. On the desktop, I have 3.0 and was using a hub. Got rid of the hub and went straight to the motherboard connection on USB 3.0. Much better but not perfect. I then moved my external drive to a USB 2.0 connection on my desktop and I am not experiencing any problems. Both laptop and desktop are running Win 10. I went thru all the system menus to make sure both machines were configured the same (where they could be).
For those following, the conclusions may suggest:
Running a USB hub may not be optimal. (in fact, initially I was running a hub off of a hub off of the mother board - i.e. chain of 2 hubs)
My PC may have USB 3.0 issues
LR may have issues with USB 3.0. If so, this would have surfaced long ago I would think.
My PC may have a virus. I have done several scans with no virus hits. I haven't yet but plan to look at the registry to see if there is some bogus item there.
While running on the laptop, I built standard previews of about 31,000 photos (after erasing the previews folder). It took almost 2 complete days but didn't crash.
I am currently making a copy of my catalog and photos on another external drive. Both hooked up USB 2.0 on the desktop. It has been running for over 2 hours and shows 9 more hours to go. Approx 480 gig to copy. So far the copy is going fine.
If any of this is something you have dealt with, please let me know.