Solved Build # appears on Desktop

[borgus]

***Automated activation process took care of it.***

"Windows 8.1 Pro and build # appear on Desktop" - which means it's not activated...

When I attempt to activate, the last five characters of the string are shown, so it knows who I am.
Enter the full string and it reports "this ID is being used by another PC" (which it's not).

The ID on the Desktop does vanish, but Windows still says it's not activated.
It was activated years ago, and until now has not prompted for same. So the query: how to reactivate?

 

[tnt4him]

Thanks for all your help. I successfully loaded 8.1 by changing the boot in bios to CSM and disabling secure boot. Everything is great, now just have to reload all the programs. This is my first time on this forum and you guys are real pros. Bookmarked it just in case there is another thing to tangle with.