David, You need to add/edit the "Log" value as a REG_SZ, under HKLM/Software/RealVNC/WinVNC4 and set the value to "Connections:file:1" in order to have connection information logged to a file. You almost certainly want to have something more like "*:file:0,Connections:file:1" instead, though, so that errors are also logged. Wez @ RealVNC Ltd.