Sorry I didn't get back sooner, BDAqua, and thanks for your interest. It has just been a busy time. In answer to your question, I just start up by pushing the button on the back of my iMac. Nothing more interesting or fancy than that. My problem is that often it doesn't boot up into OSX but into what looks like Linux to me. I am an ex-software engineer but not on macs and it has been a decade since I worked on linux, but I'm pretty sure that's what I am looking at. I type exit when what I take to be linux console messages stop and then OSX starts up.