I installed Remote Desktop Freeware on one of my colleague's computer yesterday, and after doing some tests we noticed that each time she wanted to disconnect from the remote computer by clicking on the disconnect icon, the rightmost icon which looks like a door, the program freezes and she has to close all windows by right-clicking on the active task in the taskbar. When I say all windows, that's because Remote Desktop keeps asking whether to let remote auto-detect what to do when disconnecting, even though we checked the box to not ask about this in the future. The first time we disconnected and checked the box, it went fine. Now, every time she disconnects this window reappears, with the box unchecked, and we have to forcefully close the program because it is frozen. The two computers are running on Windows 10.
Can you verify what versions you're running at both ends. You might want to just try cycling the service on the remote side see if that fixes the issue.