When you try to start Microsoft Office Outlook 2003, the program does not start. Additionally, you receive the following error message:
Do you know....this issue may occur if you install and then uninstall Microsoft Office Outlook 2007 Beta 2 on a computer that has Outlook 2003 installed. When you uninstall Outlook 2007 Beta 2 version, the Outlook 2007 Beta 2 version of the MSMapi32.dll file is not removed from the following folder on your computer: "C:\Program Files\Common Files\System\Msmapi\LocaleID"
Please view this useful MSDN KB Article. It has the information about the issue, its cause, resolution for this issue