Troubleshooting cannot boot into Safe Mode
Problem: You installed the 180 day evaluation version of Windows 7 or Windows Server 2008 R2 on a computer. Before the evaluation period expired, you used the command slmgr /ipk public_kms_client_key to install one of the public KMS keys listed in the following blog post:
Everything seems to be working fine with your computer, except that when you try to boot it into Safe Mode the computer reboots itself after logon. Why does this happen?
Resolution: You should not follow the advice in this blog post. As the following KB article indicates, converting an evaluation version of Windows to a retail/VL version is not supported. While the conversion process is not blocked and appears to work (the desktop no longer has "evaluation" on it and the Winver command no longer returns "evaluation" when you run it) the fact is that this conversion process does not remove the Windows License Monitoring Service (WLMS) from the installation, so the Windows installation is still an evaluation version and not a retail/VL version.
The bottom line is that you should never install an evaluation version of Windows on a computer you will be using in your production environment. The only way to resolve the above issue is to reinstall Windows using retail/VL media.
Mitch Tulloch is a eight-time recipient of the Microsoft Most Valuable Professional (MVP) award and widely recognized expert on Windows administration, deployment and virtualization. This tip was excerpted from his new book Installing and Configuring Windows Server 2012 Training Guide published by Microsoft Press which is available from Amazon. For more tips by Mitch you can follow him on Twitter or friend him on Facebook.