Jsut as an addition to this, I recorded a part using Play QL Pianos in Cubase 6 and the notes were sticking. Saved the file and reopened it in Cubase 5 and it played fine. Then saved it and reopened it in Cubase 6 and no more sticking notes. BUT if I recorded new piano further down on the same midi track in the Cubase 6 project, notes started sticking again.