Sorry, need a post before I can link to the solution...
---------- Post added at 20:07 ---------- Previous post was at 20:06 ----------
http://forums.logitech.com/t5/Headphones-Headsets-Microphones/G35-Audio-Stuttering-8-50-Logitech-Gaming-Software/td-p/1085265
Downloaded driver version 8.45.88 and the problem disappeared.