"negotiate protocol" and UltraVNS as windows service

[MScherfling]

I know this topic of "Negotiate Protocol" comes up all the time, but here's a new twist. I'm running UltraVNC as a windows service on a w2k server.

a) I can connect from a viewer without a DSM plugin with UltraVNC running as a service.
b) I can connect using MSRC4Plugin_NoReg v1.2.2 if I have the UltraVNC server running from a logged in window in my system tray
c) I *cannot* connect from a viewer using MSRC4Plugin_NoReg if UltraVNC is running as a service.

I've set the environment variable %msrc4pluginkey%. I also see the plugin set in the system registy: HKEY_LOCAL_MACHINE\SOFTWARE\ORL\WinVNC3\DSMPlugin. I even changed the service execution to include the -plugin parameter: "C:\Program Files\UltraVNC\WinVNC.exe" -service -plugin MSRC4Plugin_NoReg. It appears as if the service doesn't know about the plugin.

Any ideas?