I've searched and not found anything addressing this, so I hope I haven't overlooked an obvious answer.
As I've been writing this summer I've stumbled on to a strange quirk in the snare voice when adding technique or expression text including the word ";rim";. For example, an instruction that reads ";RH Rim"; or any instruction that contains ";rim"; causes the playback to become all shots. I'm adding an image file to explain myself better and a link to an mp3 of what's going on. A friend has also encountered this problem. Same circumstances. He's running Windows (XP I think) and I'm running Leopard. The problem goes away when you delete the text. And what's even stranger, as far as I can tell, putting an ";s"; on rim fixes it. So, rim=rimshots, rims (with an s) is fine.
I'm still using Sibelius 5.1 and VDL2.5 with the latest template. No issues other than this.
Now regarding the ";strange quirk"; you referred to. ";rim"; is one of the default staff text items in the Dictionary, of which none were changed for the Template. When you have ";rim"; in the score as technique text, Sibelius is trying to do a sound ID change, which in this case the net result is a sound you don't want.
I could go on and on about this; for another day maybe. But let me know if you need more than what I just gave you.