Some new KBs for Tshooting Outlook Calendar Issues
971878 Steps to enable Exchange 2007 store tracing for calendar issues
https://support.microsoft.com/default.aspx?scid=kb;EN-US;971878
971435 Steps to enable Exchange 2000 and Exchange 2003 Calendar Store tracing
https://support.microsoft.com/default.aspx?scid=kb;EN-US;971435
970920 Using Process Explorer to List dlls Running Under the Outlook.exe Process
https://support.microsoft.com/default.aspx?scid=kb;EN-US;970920
Master Doc (old)
Working with support to troubleshoot the Outlook calendar in an Exchange environment