Hi there,
Maybee these things below are a starting point to find your problem
How much hard drives do you use and how is the load spread out (1 disk = OS + softw, disk2 = audio + projects, disk3 = sample libraries?), are your disks on dedicated controllers? Are you measuring the load of these disks?
What motherboard do you use and is it with the lastest firmware. Is there any tweaking done on your motherboard. How stable is your RAM? etc. etc.
Why all these questions you might ask?
Simple said your cubase should work! Drop outs merely indicates that something is wrong and you need to find out what. If all users suddenly are saying they get dropouts then I would look first at Cubase, but since this is not the case, I would look into hardware and driver problems.