ok in the lister (i do dual vertical) when you click on an existing folder i get a "reading folder" progress bar and even for tiny folder it takes a while - the file is local on my C drive - this problem just started today - hopefully no MS updates adversely effected DO. but i might re-install DO if this continues. its so bad on remote linux filesystems that DO stops responding - ive used DO for some few years not without incident until today 
Is there some 'logfile" that DO keeps that might help identify the issue?
There's no log that would identify that kind of problem, but using Process Monitor to see what is being accessed may shed some light on what's happening.
Does Windows Explorer have similar problems reading the same folder?
Does the folder have any shortcuts in it, in particular ones which point to network drives which may not be available?