Please give me a clue guys... My laptop with Windows 8.1 update 1 was activated with a MAK key, phone method (before update 1). No problems at all until i applied update 1. For the last couple of months my installation shows an erratic activation behavior. Many times when i turn it on, i see the "Windows 8.1 enterprise build 9600" watermark on the corner (although My Computer-Properties showed it's activated) , and a couple of times it prompted me to reactivate. Even My Computer-Properties showed i am NOT activated. Usually a reboot cycle fixes it. WTF???
Have you disabled some hardware? it happen to me when i disable my lancard and/or replace my IDE controller driver.
Hm. recently I cloned a 1TB HDD to 1TB SSD using Clonezilla. Unplugged old disc and plugged in new one without loosing neither activation of Os nor Office 15
on other computer, i have tray replace my Notebook Harddisk, and no problem with my activation. and other test, i have replace my PC VGA Card, and no problem too. all still activated.
HD serial number only takes 1 strike IIRC and it requires 4 strikes to de-activate. HD + different MAC address would do it.
This is usually from either changing key on accident, or from hardware (sometimes even driver) changes. I've heard stories about installation id changing from simply changing a driver. I suspect that Windows is somehow using the complete hardware id string as the hashing component and if one part of the string changes, it might change the whole thing. That is just speculation though... it would require some testing. In the meantime, why don't you try verifying that your MAK hasn't changed to the KMS key if you've been playing with a KMS activator for office and changed Windows activation on accident.
I have that on (dual boot) Windows 8.1 up Pro at times, the Enterprise is always OK, what I do is go to MS and Let them check Activation, and it goes away.... I click the "watermark Get Activated now" and it goes away ... now remember this only happens at times and it on a Dual Boot System - and only when I select Pro