Sorry guys, after many frustrating hours trying to remove Roxio 9 and go back to the much more useful EMC 7.5, I am now convinced the only way to remove Roxio 9 is to back everything up and format the hard disk.
I'm very grateful for the large amount of help and suggestions on the forums relating to this problem, but none of it worked (including Roxio's own deep clean procedure).
My main use is audio, and like several other correspondents, cannot understand why Roxio insists on developing good features (like ver 7.5's overlap / crossfade routine) then trashes them in the next release.
Good thing we have a long break this Christmas!
2.8Ghz Pentium dual core
1x 320Gb IDE
1x 320Gb SATA
1x DVDRW IDE
1x DVDRW SATA
Soundblaster Live 5.1