You might need to update your BIOS for COD MW4 online play

TPM and Secure Boot requirements strike again.
Indiatimes on MSN

How to fix new key failed to generate and attestation failure in Call of Duty: Modern Warfare 4

Modern Warfare 4 players encountering attestation errors can check Secure Boot and TPM 2.0, update their motherboard BIOS, ...
XDA Developers on MSN

Your CPU got faster after you bought it, but only if you installed one update

Turns out there is a free lunch after all, and it's called a firmware update ...