About the Error
After reinstalling and using a new product key, you may see the error code after attempting to activate the Windows 7 RC.
Windows code 0x80072f8f - Read what really helps
This is a simple one to fix. It is a date and time setting conflict. You need to verify and adjust the date and time settings, and then the error code will disappear and you can proceed with your activation. In the Date and Time dialog, change the date and the time to the correct settings. Click OK, and try your update again.
TipFor more information, please see: How to fix System error #0x80072f8f