Why do I receive an ngina.dll error when I use Windows XP's Remote Desktop feature to attempt to connect to a remote machine running Lotus Notes 5?

A. Lotus Notes 5 includes a Client Single User Logon option that lets a user access Lotus Notes without entering a password. Systems that use this feature run the Lotus Notes version of ngina.dll. When you attempt to connect to such a system, an incompatibility with the XP Remote Desktop version of ngina.dll results in the following error:

"You cannot initiate a Remote Desktop Connection because the Windows logon software on the remote computer has been replaced by incompatible software ngina.dll.To correct this problem, please have the administrator of the remote computer contact the program vendor for a version that is compatible with Windows."

Lotus Notes always installs its own version of ngina.dll but only enables this file when you use the Client Single User Logon option. This option is set in the registry at the HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinlogonGinaDLL registry subkey.

To resolve the error, uninstall then reinstall Lotus Notes 5 without enabling the Client Single User Logon option. Although you might be tempted to simply delete the GinaDLL registry value, this action will corrupt the Lotus Notes single user logon feature.