Very often opens blank window that couldn't be closed. Helps only click on the Show menu and then close (x) button on the normal (not empty) window.
What windows version are you using?
I use macOS for both sides server and client. Monterey 12.2.
Could you do this:
1. Stop and exit the virtualhere client
2. Download this new build https://www.virtualhere.com/sites/default/files/usbclient/test/VirtualH…
3. Run that new beta build of the client instead and tell me if that resolves the issue.
It seems to work fine. No one empty non-closing window during the day.
OK I have pushed this fix into Client release 5.2.9 now available on this website