The problem is not with an extension...
All extensions work great in CS3. As far as I can tell, the problem is with the installation.
None of the files the extension is looking for when it is launched are in the proper folder.
Please read the message I posted just before your response. I have uninstalled and reinstalled extensions, removed the Cache file but nothing ever changes.
You may have noticed that all the error messages I attached are pretty much identical so it is not an issue with installing an outdated extension like PhotoAssist.