_ [debian] vnc4server 4.1.1+X4.3.0-35 変？
I kept hitting this issue (and #428305) for a while. I believe also that 428305 is related. Now I got VNC stuck and I think that I had a screen in ssh session running within VNC – that one got stuck too.
vnc4server が 100% になってるかどうかは確認したことがなかった。今度固まったら確認してみよう。