Foreground's update, caused by GAMESTATE->m_fMusicSeconds moving backwards.
This happens due to frame skips confusing GameSoundManager::GetFrameTimingAdjustment.
It expects that, when the framerate is stable, each frame will take 1/FPS.
If we skip a frame, it thinks one frame is 30ms late, and tries to
adjust by 30-16ms. Reduce the threshold for this adjustment to half a frame;
if we're that much late, the problem isn't scheduling jitter--we've probably
dropped a frame, and adjusting here is incorrect.
In case that isn't enough, clamp fDeltaTime in Foreground, too.
Glenn Maynard