office won't open from outlook

When I get an Office attachment in an email (Outlook 2010) the attachment won't open. I have to save it and then open it with the appropriate Office program. If I click on the attachment it prompts me to sign up for Office or enter a key. I already have Office installed. Again it is only on 1 of the 3 computers in my office that is doing this. Any ideas?

 

Sounds like Outlook may not be activated on that system. In Outlook 2007 it's Help > Activate and Help > About, the latter stating the registered licence owner.