Actually, I have experienced this as well even after the update. Try cutting back on the level a bit in the kontakt player if you are using one. It worked for me. Cymbals tend to push the envelope and break up at higher levels and some FX\'s may add to the problem as well. See if this helps and if if not maybe the GPO team can help further.
Hope this helps some.
I’ve experienced problems like this, only to find that I was playing my midi tracks along with bounced ones, thus recording the track on top of itself. I\'m sure it\'s not GPO, since we have many demos with cymbal rolls without any problems.