Outlook 2010 - make it use the only profile automatically

Check this page, specifically the section towards the bottom "How to configure Outlook 2010, Outlook 2007, and Outlook 2003 to open a specific email profile". I think it's a control panel setting you need to change.

Go to Control Panel → Mail → Profile → Show Profiles, and check "Always use this profile" for Windows 7 with Outlook 2007.