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#11
Right click on start icon, select Command Prompt (admin). Run slmgr /dlv
Post the result window here and we can likely tell you what is wrong. It's very interesting because this webpage shows -GVGXT as being a product key for Office 2013:
GVLKs for KMS and Active Directory activation of Office 2013
I expect that you have a KMS activation, which SLMGR /DLV will tell us.