POL: Projects losing macro/VBA on start up in MS Project...

Hi Team

We have POL. Most of the time PMs use MS Project to access their projects which are stored in POL. For some strange reason, some of the project files 'lose' their macros. This is on on-start. The two macros are not very complicated and it includes a little XML to add and remove a ribbon tab. But it doesn't do this for all the projects.

Has anyone seen this before and know what to do?