Tracks visually fine but playback is off time.

I recently backed up my mack and wiped it. installed el capitan and now when i open my cubase 8 pro projects the tracks are in the right place but there are a least one if not more tracks that are playing about 1 sec behind the rest of the mix. I have also lost a track on one session and am not sure what to do i have never had this kind of problem before with cubase it has always just worked.