Hello WJM,
You can set Project to open the last file on startup in Tools > Options,
General tab. However, I believe there is currently an error in Project
2007 where opening the last file on startup causes an incorrect error
message.
When you open an existing project plan the Project1 file is closed for you.
I guess I'm not sure that a clicking a button to run a macro is any
better than using the built in close button or CTRL+F4
I hope this helps. Let us know how you get along.
Julie
Project MVP
Visit
http://project.mvps.org/ for the FAQs and additional
information about Microsoft Project