Lotus Notes 8.5 supports both Notes client single logon (introduced in an earlier release) and Notes shared login (new in 8.5).
Notes single logon is not a supported configuration if you use the ID vault. Therefore, if you use the ID vault, use Notes shared login instead, which is designed to work with it.

If you enable Notes shared login in a policy, the policy takes effect only on Lotus Notes clients that do not have Notes client single logon enabled. If you now use the Notes client single logon feature, you will need to disable it before Notes shared login can be enabled on the Notes client.

For more information about the Notes shared login feature and to see if this feature will work for your organization, see the help document "Using Notes shared login to eliminate Notes password prompts" at the IBM Lotus Notes and Domino Information Center.

To upgrade from Notes single logon to Notes shared login, follow the steps below:

If you are upgrading from an earlier release to Lotus Notes 8.5x:	Run the Notes installation program to upgrade Notes and de-select the Client Single Logon Feature. Steps: 1. On the Lotus Notes 8.5x installation Custom Setup screen, click Notes Client -> Client Single Logon Feature -> This feature will not be available. . 2. Continue with the install as normal. The older Notes single logon feature will be uninstalled. Afterwards, if the user is assigned a policy that enables Notes shared login, the user will be able to use the Notes shared login feature.
If you are already running Lotus Notes 8.5x and not performing an upgrade, but have access to the Lotus Notes installation program:	Run the installation program and de-select the Client Single Logon Feature. Steps: 1. Locate and run the Lotus Notes 8.5.x installation program, and on the Program Maintenance screen, select Modify and click Next. 2. On the Custom Setup screen, click Notes Client -> Client Single Logon Feature -> This feature will not be available. 3. Click Next to continue with the install process as normal. Only the Notes single logon feature will be uninstalled, and no other changes will be made. Afterwards, if the user is assigned a policy that enables Notes shared login, the user will be able to use the Notes shared login feature.
If you prefer to run the Lotus Notes installation program using silent install:	Beginning in 8.52, you can use the new Notes MSI installer commands (REMOVEFEATURES) to uninstall Notes single logon during a Notes silent install or upgrade. For example: setup /s /v"REMOVEFEATURES=ClientSingleLogon/qb+" For more information, see http://www-01.ibm.com/support/docview.wss?uid=swg21424066
If you are already running Lotus Notes 8.5x, are not performing an upgrade, and do not have access to the Lotus Notes installation program:	The Notes client single logon feature is considered disabled if the "Lotus Notes Single Logon" Windows service is removed. Steps: 1. You may use the Windows utility SC.exe to remove the service using the below command: sc delete "Lotus Notes Single Logon" (You must be logged in as a user with the required permissions to run this command.) Microsoft Windows documentation for SC: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/sc.mspx 2. (Optional) After removing the service, you may also want to rename or delete the two Notes client single logon files from the Lotus Notes directory: nslsvice.exe and npnotes.dll. Note: Using the Lotus Notes installation program to remove the Notes client single logon feature is the most straightforward and cleanest method. Disabling the Lotus Notes single logon feature in the method described above has not been extenstively tested on multiple platforms.