Hi Brian,
You didn't provide the exact error message you are receiving when trying to send mail, but the following Knowledge Base (KB) article addresses issues with the MSO9.DLL file.
Please refer to Knowledge Base article:
OL2000: Invalid Page Fault in Module Mso9.dll (241817)
You can access this article by clicking on the link below.
http://support.microsoft.com/default.aspx?scid=KB;EN-US;241817
Regards,
Scott Atkins MCSE, MCSA
Partner Technical Lead - Outlook
Microsoft Technical Support
for Platforms and Business Applications
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>Content-Class: urn:content-classes:message
>From: "Brian Dickinson" <brian@dickinson-home.co.uk>
[quoted text clipped - 22 lines]
>please.
>Brian