Looks like you're enjoying the discussion, but you're not signed up for an account. When you create an account, we remember exactly what you've read, so you always come right back where you left off. You also get notifications, here and via email, whenever new posts are made. You can like posts to share the love. 
Join 
An unauthorized change was made to Windows
Windows has discovered a change that will result in limited Windows functionality. Use the link below to find out how to fix Windows.
Two Options: Learn More Online, and Close.
Or:
An unauthorized change was made to Windows
You will no longer receive notifications, including those about your license or activation.
Error: 0xC004D301
Description:
The security processor reported that the trusted data store was tampered with
Two options: Learn More Online, and Close.
If you click Close on either of these windows the user is logged off and you are taken back to the Windows welcome screen. Learn more online will open the default browser and allow you to navigate the web for solutions.
I have found the solution to resolve this issue of "deactivation," if that is what it can be called.
In order to resolve the problem, use the Learn More Online button so that the default windows internet browser will open. In the address bar, type file://c:/windows/system32 and press enter, or change the path to whatever the local path is for the windows\system32 folder.
The browser will list the files in the c:\windows\system32 folder. Find the "cleanmgr.exe" file which is the Windows Disk Cleanup utility. If using Firefox you have to click to save the file and then double-click the file in the downloads window to run it. I noticed that in FireFox it also did not display them all in alphabetical order. There were two groups of alphabetical files, and I found cleanmgr.exe in the second group.
Once Windows Disk Cleanup starts, it will ask if you want to clean files for the current user only or for all users (this prompt only appears if UAC is on), choose the option to clean files for all users. You are then prompted for which drive to cleanup. It is usually the C: drive. When the disk cleanup window opens, accept the default checked options and click OK. Disk cleanup will finish and the window will close without confirmation. At that point, close the internet browser and then click "Close" in the error message window that is still on the screen. You will be logged off, and you can choose to restart the computer from the Windows welcome screen.
Once Windows restarts, at login, it will then prompt for Windows Activation saying that activation information has changed and you need to re-enter the Windows product key from the COA sticker on the computer. Re-enter the product key, it should be accepted. At this point, you will have to have an active internet connection or will have to activate by phone. Once activation is complete, reboot one more time for good measure and the system will be back up and running.
If for some reason Windows did not prompt for activation in the previous step, you will have to go straight to control panel (which you will notice is only partially functional) -> system and maintenance -> system and choose to reactivate windows and enter the product key that way.
