Deploy the Infrastructure Update for Office Project Server 2007
If case you have missed it, there is a useful TechNet article that describe how to deploy the Infrastructure Update for Project Server: https://technet.microsoft.com/en-us/library/cc671413.aspx
The equivalent SharePoint article is here: Install the Infrastructure Update for Microsoft Office Servers (Office SharePoint Server 2007)
and in case you missed it: Announcing the availability of the Project and Project Server 2007 Infrastructure Update