MIDI Drops in and out

I have a drum sampler VST which is being triggered by a midi sequence (on the same track) The drums will randomly fail to trigger, leaving holes in my drum sequences (like suddenly a snare won't hit or something) I dont really have this problem with anything other than drums Also, occasionally the first midi note of a region will play at half-velocity, no matter what the actual velocity is I'm running v3 on Windows Media Center (32bit)

Did you ever find a solution to this issue?

and what is the vsti drum? must have a name, yes?