Excel 2007 : Places Bar

Each day when I first open Excel 2007 SP 2, I get a small window that says:

Initializing Places
Initializing the Places Bar

A very slow moving green progress bar moves across the bottom of this small window for about a minute. I cannot Cancel this process and the X at the top right of this small window does not stop the process and does not close the window.

Does anyone know what this is about and, most importantly, how do I stop this from happening?

Please reply to <[email protected]>

Thank you.

Cal