I didn't have any experience with Mac. I purchased the iMac from B&H in November last year but B&H bought it in July. The Apple guy over the phone told me It was 19 days out of warranty.
He also told me the trouble shooting was $49 and I agreed to pay. It was so easy to fix the problem by repairing the hard disc from the installation CD. if I knew the sequence to boot from a CD I would have done it myself.
If any one has the same problem, i.e., you only see a flash "?" after you turned on the iMac, I can offer a advise to fix it at the expense of $49 + tax….哈`