Huh!! On my PC it happens at least 4 out of 5 button presses to the stage where i was going to dispatch my touchscreen with an angry left after getting Hard Dance music at full wack at 6.30am in the morning having fled the car the night before.
P4 Celeron 2.2 - 512MB - OPUS 250 - Audigy SE - BU353 - HQCT - No Speakers though :-(
FWIW, it did happen on my regular P4 3 Ghz. But I think it only happened with single-click mode turned on. Just so you're aware, this is something to be tested under those conditions before rleleasing rc3!!!