This is the downside to having multiple versions installed,
http://support.microsoft.com/kb/828967.

You could try re-registering Visio components by going to Start/Run/type
visio.exe /r. If that doesn't work, try starting Visio 2003 and let it
repair. Then exit 2003 and start 2007 to see if that fixes the problem. If
that doesn't work uninstall 2007, then uninstall 2003. Then install 2003,
then apply 2003 SP3, and then 2007, then 2007 SP1.



Best Regards,

Aaron Rykhus, Visio Support
Microsoft Corporation
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This posting is provided "AS IS" with no warranties, and confers no rights.