Audio dropout

I had an audio dropt out tonight at my gig and had few audio drops in da past in the two updates,4.0.2& 4.0.3 mac version (specs:i7,16 gig ram,500ssd)),i never had this in 4.0.1,also wats the problem,till now the windows version crashes so why ? I have to put in the setting waveform screen rate or resolution to low so that it doesnt crash .