> Is the Windows firewall configured to accept VNC connections? bingo, thanks. xtightvncviewer paints the screen right away, ssvncviewer leaves the screen black until wherever the mouse is moved, but shows certain widgets reliably, where xtightvncviewer only shows said widgets when the actual (not virtual) mouse is moved there. xvnc4viewer seems to suffer neither shortcoming. so all (more or less) compatible with ultravnc afterall.