To resynchronize your computer's clock to the network's clock,
manually set it, or run the leash Synchronize Time Command. If
you are using Windows XP or Windows 2003, the Date and Time Control
Panel contains an Internet Time page which can be used to automatically
synchronize the clock on a regular basis.
Why Do It...
Kerberos authentication uses time stamps as part of its protocol. When the clocks of the Kerberos server and your computer are too far out of synchronization, you cannot authenticate properly.