This is a troubleshooting post.
Windows explorer may stop responding when left (or right) clicking a folder. The explorer is freezing or freezes for some time, typically 30 seconds. After that you can access the folder. Attempts to close the folder while the hourglass is turning results in an error or message “This program is not responding”. You can either end the process, after which explorer restarts, or cancel.
In my case I found windows looking for Network Drive letters. I noticed that using Procmon, a process monitor.
Just after the explorer had touched a .lnk shortcut file.
It seemed windows, when clicking the folder, looks trough all the files and then discovered a shortcut to a network drive that doesn’t exist. It was an old shortcut pointing to a fileserver that doesn’t exist anymore. The query typically times out, but that takes a while.
The problem was solved by removing (deleting) the shortcuts.