Has anybody else had this problem with their mac computers?

We have a mac (one of the newer, non-portable ones) and last Summer it wouldn't turn on. As in, it was all fine one day, and then the next day it just had no power. We had to send it away to be fixed for 8 weeks until we finally got it back. This, unfortunately, has happened again yesterday and our computer has been sent away...again. I always thought that macs were supposed to be such good quality but I've had a Toshiba as long as the mac and have had zero problems with it whereas our mac has now been sent away for repairs twice in less than a year. Did we just happen to get the one faulty mac or are any of you having this problem?