Macs, PCs and such are not maintenance free. I'm wondering if this machine got it's yearly cleaning. If you don't do this yourself then tell about your yearly trip to the shop.
Example for a PC at http://reviews.cnet.com/4520-11319_7-6240575-1.html
Hi ..I have a Mac OS 10.4.11 power Mac#W8446232PP7..... and recently it just turns off on its own, which means I have to pull the main power , re-plug it in and press the start. Is it in its death throes or would a thorough cleaning save it. Thankyou