Copy of Microsoft Office is not Genuine

I am getting a invalid key error on my system. I am using a Volume Licensing method to activate a bunch of office installed around the work station. Due to some issue I had re-installed each and everything back again. But when the time comes for activation again it is not detected as a valid copy. What am I doing wrong here.

You have to contact Microsoft for that. It looks there is some kind of bug you are facing due to licensing. I had faced this issue with Office 2003 re-installation. I got some fixes from Microsoft which resolve the issue.