vnc screen is freezed, not fixed by rebooting

Question

I had several programs running on a server, which I connect to with VNC Viewer. And for some reason firefox became unresponsive, and the screen froze. I followed these steps:

1. vncserver kill -9 :1 to kill the process
2. vncserver :1 to start a new one
3. sudo reboot

However, when I reconnected, the screen was still frozen and I could not even move the mouse cursor. Here is a screenshot:

Answer 1

Whoops! I found the reason for that, I had mistakenly checked the view-only checkbox. Here is the screenshot: