MS Office trouble

Problem
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Users having:
- Office 2003 (sp3) with Office 2007 compatibility pack (sp1).
- Office 2007 (sp1)

work on the same document on a smb share.

From on point in time, the user using Office 2003 gets:

"Filename.ppt is currently in use. PowerPoint can't modify it at this time."

when he tries to save it (even if no modifications done).

Cause
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The user with Office 2003 has inserted some excel tables as embeded (instead of graphic). This article appears to apply: http://support.microsoft.com/kb/285517


Solution
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Using Office 2003 , copy/paste all slides to a new powerpoint and save it as Office 2003. Then replace the pptx with this one and instruct the users to use this ppt instead (and save it as ppt no matter if they use 2007/2010).