Comment # 2 on bug 1042764 from Ruediger Meier

(In reply to Stefan Dirsch from comment #1)
> Does not happen without Xserver reset:
> Xvfb :99 &
> DISPLAY=:99 xterm &
> --> *No* Xserver reset
> DISPLAY=:99 xdpyinfo
> DISPLAY=:99 xdpyinfo
> --> No problem ...

Sounds similar to that old Xephyr bug #867483.