Whenever I put a couple of tracks into the sequencer and listen to them back I sometimes hear (say every 4 or 5 bars) a strange sort of "freezing sound". It's as if the tracks or vst's temporarily freeze for a split second and then everything goes back to normal. When I look at the vst performance meter everything looks okay (it peaks at around 50) but then it suddenly jumps to 100 (into the red) and I get that weird sound and then back to 50 again. What is this and how to I correct it?

Any replies appreciated.