Microsoft executioners have started the expiration process for the beta version of its Windows 7 operating system.

Beginning today, users that are still running the trial version of the company's next OS will see it shut down every two hours. The big idea is to shift early adopters to move to Windows 7 Release Candidate, a more polished preview version of Vista's successor.

Windows 7 RC will function until June 1, 2010. After that, users will need to upgrade to a full, paid version of the operating system to continue use. Microsoft plans to ship a final version of Windows 7 on October 22.