I have a WordPress multisite install. I am having a problem whereby empty directories are occasionally being created (not by me) in the root directory whose names match the names of some of my WordPress sites. Because of the way .htaccess is set up for WordPress, if these directories exist then the site does not display.
It's the same problem as noted here without resolution. It seems likely that something is automatically creating them, but I don't know what.
It happened about three weeks ago and again today. The intermittency means it's hard to test. Any suggestions on how I could go about investigating this?