Make sure to have installed the latest 6.7.
Then, deactivate the GPU an see if this helps: Adobe Lightroom GPU Troubleshooting and FAQ
If it does not help, reset the preferences: How do I reset Lightroom's Preferences? - The Lightroom Queen
If the issue persists, let us know more about your hardware.
If you still have problems after following F.McLion's suggestions, try a full reboot (ie power off to computer followed by booting up). Windows 10 'fast start' seems to cause problems after Windows does an update in the background and a reboot seems to sort it out.
Good point. Fast start really has many issues - I actually recommend to turn it off anyway.
I always forget to write about a reboot. To me this is like the first thing anyway ... used to older Windows
Thanks for all your suggestions, but none of them work.
I have reset preferences, disabled GPU, update GPU, update to LR6.7, rebooted (cold reboot), etc.
Sometimes I can work for awhile, and sometimes I cannot click on a new folder without going into the "not responding" mode.
If I look at task manager LR6 is using increasing memory as it sits there not responding.
Anyone have any ideas?
Is there a phone help line from Adobe?
There is another quirk I have noticed in my LR6.
My "Collections Folders" no longer appear below my working folders.
I only can see my Collections if I collapse my Folders and vice versa, I have to collapse my Collections to see my folders.
What you are describing is "Solo mode". Right click on one of your left panel headings and make sure there is not a checkmark in Solo mode if you don't want your different displays collapse. In solo mode Lightroom automatically collapses other sections to preserve space for the one being used.
I am not in Solo mode.
I have checked carefully all that there are no check marks in any of the left panel settings.
The unresponsiveness problem generally occurs when I click on a file folder within my left panel list.