Dennis:
I would suggest using the running the following registry file to resolve the conflict between the Visio 2003 template and the ArcGIS 10 dll files in order to get the Semantic Checker to work in verion 10.
http://resources.arcgis.com/gallery/file/geodatabase/details?entryID=446C6FCE-1422-2418-34D3-EB09E97...
Shana B.
ESRI Support Services
I'm having the same ClassFactory problem mentioned above. I'm using ArcGIS 10, Windows 7 64bit, and visio 2003, and I have followed the instructions mentioned in KB38058, and the registry patch.
Regards,
Ahmed