Since it is impossible to install or uninstall software asynchronously (after all, the user may be using the application as the uninstall begins), it will take up to two logons before software that is delivered through the directory will install on Vista machines that are using fast logon optimization.

When you log on, the machine identifies that a software package is ready to do its thing. So it sets a flag to affect the change at next logon. So the next time you logon, GPOs are applied in a synchronous manner to allow the software installation to proceed. Once applied, GPOs are reset to asynchronous.

Of course you cannot redirect a user’s Documents folder while the user is using it. If you use folder redirection, it can take up to three logons before the policy is applied: The first logon updates the user security group memberships. The second detects the change and sets the flag for synchronous GPO application. The third applies the change and resets the GPO processing mode to back to asynchronous.

One of the ways that fast logon optimization speeds up the logon process is by caching all user logons. So if you make a change to a user’s properties such as changing their profile from local to roaming, it won’t be applied until after two logons: The first updates the cached user object and the second actually applies the change.

Note: If a user has a roaming profile, fast logon optimization is automatically disabled for that user.