A particular model usually won't boot from anything older than what it shipped with. On Feb 9, 2010, at 11:59 AM, Paul Moortgat wrote: > On a new Mac Pro one need 10.5 instead of 10.6. I called Apple because 10.5 would not install. ----------------------------------------------- There are only three kinds of stress; your basic nuclear stress, cooking stress, and A$$hole stress. The key to their relationship is Jello. neil