Hi Nick,
Those types of error messages are usually generated when there is a corrupted game file if my memory of playing WoW serves me right. However, if we're going to determine if it's an issue you have with the HD 4000, we'll need a copy of your dxdiag. Can you post one so we can look please? (Start -> Run -> dxdiag -> Save All Information).
Thank you,
-Nic
