incorrect save message

[Kerry]

We have a new project manager with a plan in project server. When he goes in
to his plan, he gets a large message box, larger than your normal message
box, saying "do you want to save changes to "project name". To our knowledge
there are no changes to it. If he says yes, it just locks his machine. Other
PM's can open, modify and publish the plan, without getting any popups. He
just starting using Project Pro and Server, so I'm thinking it's his set up.
But I've checked his options, and they look good to me. Any ideas?

thanks for your help.