For the past two weeks, users of the Windows 7 Release Candidate have been seeing a warning message stating that the operating system would soon begin shutting down every 2 hours to encourage the move to the release version, made available back in October 2009.

Today is that day folks, if you are still using the release candidate, your machine will begin shutting down without warning every 2 hours.

On June 1st, the operating system will switch over to “non-genuine” mode, turning the background black and displaying a warning in the lower left corner, stating that “This copy of Windows is not genuine”. While the release candidate will still function, it will not be receiving security patches or bugfixes, so users are advised to upgrade to the retail version of Windows 7, or reinstall a previous version of Windows, such as Vista or XP.

The Windows 7 Release Candidate was one of Microsoft’s largest public tests of a pre-release operating system, allowing millions of testers, journalists and enthusiasts to use a near complete version of the OS without having to pay or wait for the final release.