The Register posted an article that many Mac users are having problems on installing the latest Mac OS that they have bought which is Leopard. It is version 10.5 of the Mac OS X.

One of the users said:

I’ve just been on the phone to Apple AU support for an hour (around half of that spent on hold, but on-and-off as they sometimes consulted other techs), and they definitely know of the BSOD issue, said they started taking calls from 9am Friday as the first (early courier!) deliveries of Leopard were installed, and they’ve been flat out, “phones ringing non-stop” since then. Implied that Apple stateside has been swamped (as you can imagine) and they haven’t been able to pinpoint the issue causing the BSOD but “they’re looking into it”.

Source: The Register