www.inkompetent.de/ knowledge base/ software/ vnc local loop-back
Your VNC server is the Windows-Version and your
VNC client exits with the following message:
VNC server supports protocol version 3.3 (viewer 3.3)
VNC connection failed: Local loop-back connections are disabled.
Add a DWORD key named AllowLoopback of value 1 to your
registry in HKEY_LOCAL_MACHINE\SOFTWARE\ORL\WinVNC3