So you don't get the error in a new project, only the ones that you used the Emu on? What format did you save them in (CWP or CWB)?
In the old project, you've deleted all references to the Emu in the synth rack and in the audio and midi preferences, right?
We need to ensure we understand the results of our suggestions so we can try to decipher what's going on.
Have you tried one of the old Emu projects using the onboard sound instead of the Saffire? If so, did you get then same error message?