Today I had an odd experience with installing Windows Server 2012 R2. I downloaded the ISO from the MSDN subscriber’s downloads. Then I got the product key from the same line item on the download page, this makes me assume that I couldn’t have mismatched the keys. Then when I installed the OS, it prompted for the key and immediate claimed that it was an invalid key. While Googling, I kept clicking next on the install page, for no other reason than my personal insanity. Oddly enough, I found out that I am insane because after 6 attempts with the same product key, not re-typed, the exact key that was in the test box, worked!
Moral of this story: insanity delivers you mystical technical powers.