This article describes the different scenarios in which the Fast User Switching feature is available. The availability of the Fast User Switching feature depends upon the following factors:

•	The version of Windows that has been installed
•	The network configuration (workgroup or domain)
•	The computer resources
•	The type of third-party software that has been installed

Back to the top

The Fast User Switching feature is available in Microsoft Windows XP Professional and in Windows XP Home Edition under the conditions that are described in the following sections.

Back to the top

Windows XP Home Edition

•	This feature is always available if you are not using a third-party product that replaces the Microsoft Graphical Identification and Authentication file (Msgina.dll).
•	This feature is enabled by default on computers with more than 64 MB of RAM.
•	This feature can be enabled or disabled in Control Panel. To do so, click User Accounts, and then click Change the way users log on or off.

Back to the top

Windows XP Professional

•	This feature is only available if the computer is not a member of a Microsoft Windows NT, Windows 2000, or Microsoft Windows Server 2003 domain, and you are not using a third-party product that replaces the Microsoft Graphical Identification and Authentication file (Msgina.dll).
•	This feature is enabled by default on computers with more than 64 MB of RAM that are not joined to a domain.
•	This feature can be enabled or disabled in Control Panel. To do so, click User Accounts, and then click Change the way users log on or off (on computers that are not joined to a domain).

Back to the top

Other limitations of the Fast User Switching feature

Computer resources

The Fast User Switching feature may not work if there is insufficient computer resources to create a new Winlogon service thread. When there is insufficient resources, the system may stop responding (hang), the system may lock up computer, or the user may receive a Userinit.exe application error and the following error message: In these cases, some users must log off the computer, or you must close some programs to free up computer resources.

Third-party graphical identification and authentication products

The Msgina.dll file interacts with the Winlogon service to provide the Welcome screen and the Fast User Switching feature. Third-party software can replace the current Graphical Identification and Authentication data with their own Graphical Identification and Authentication data. The Fast User Switching feature and the Microsoft Welcome screen are not available if you are using a third-party product that replaces the Microsoft Graphical Identification and Authentication file (Msgina.dll).

For more information about restoring the original Graphical Identification and Authentication file, click the following article number to view the article in the Microsoft Knowledge Base:

Back to the top