I have a Windows Server 2012 Machine were I need to do some development. The machine is a Hyper-V VM. I activated it with a valid key and restarted the VM. After it booted up again, I went into system properties and saw that it said that Windows is activated. However, there is still the message "Activate Windows" on the desktop wallpaper and if try to change something (for example, the look) it tells me that I need to activate first.

Is there anybody who has experienced this? The host OS is Windows 8.1. I already installed all updates and tried to activate again using this CMD-Command:

slmgr.vbs /ipk {product key, including dashes}