If you’re still running Windows 7 Beta (Build 7000) you should know that as of July 1, 2009 (*)
June 1, 2009 your computer will behave strange 🙂 (your pc will shutdown every two hours!) and on August 1, 2009 Windows 7 Beta (Build 7000) will expire and you won’t be able to use it anymore!
Please upgrade (or reinstall) your computer with the Release Candidate of Windows 7.
Upgrade tip : You can easily use the Windows Easy Transfer tool to move all your user settings to the Release Candidate build! To start the Windows Easy Transfer tool just type Windows Easy Transfer after you clicked the Start button.
You can easily backup your files/settings to a USB disk and move them back after you installed the Release Candidate.
(*) The correct date is July 1, 2009. Source : Windows Team Blog