If you're using Vista I've discovered that the fix is to run the desired program (Sound Editor, Creator Classic, etc.) as Administrator: right-click on the shortcut on the Start Menu and choose "Run as administrator". This has fixed the "Trial version has expired" errors I was getting with EMC8 and also "Certificate missing" errors with EMC7.5. Should work also for EMC9. Apparently Roxio attempts to write registration information to what Vista considers protected areas in either the registry or file system, and running as Administrator allows it to happen.
I do not yet know if it's necessary to run as Administrator every time you use EMC or only the first time. I'll figure that out eventually, but I wanted to post this right away in case it can help someone who's tearing their hair in frustration, as I was.
Also, I did this after a fresh reinstall of EMC. I don't know if this fix will work otherwise.
