Microsoft announced plans to significantly boost its anti-piracy measures starting with Windows Vista, with steps including a new “reduced functionality mode” that will severely limit what the operating system does when the product hasn’t been properly activated, using a product key, after 30 days.
Here’s an excerpt from the Microsoft white paper that explains the changes.
By choosing “Access your computer with reduced functionality,” the default Web browser will be started and the user will be presented with an option to purchase a new product key. There is no start menu, no desktop icons, and the desktop background is changed to black. The Web browser will fully function and Internet connectivity will not be blocked. After one hour, the system will log the user out without warning. It will not shut down the machine, and the user can log back in. Note: This is different from the Windows XP RFM experience, which limits screen resolution, colors, sounds and other features.
See Microsoft article on this topic here.
See the full Word document here.