http://blogs.technet.com/b/mariaj/archive/2010/02/02/still-running-the-windows-7-rc-expiration-is-getting-closer.aspxOn March 1st, the Release Candidate of Windows 7 will start to shut down every two hours until the expiration date June 1st. If you’re still not ready to move to a released version of Windows 7 you can install the 90-day trial . We recommend a clean installen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)