My old, heavily added to, Beige G3 is playing up and my Dual G5 hasn't arrived yet. When I turn it on from cold I get the 'dong' noise but then the machine just sits there unless I bang and crash it down onto my desk hard quite a lot!! Once it's running it seems OK. I thought it was the hard drive, which isn't old, sticking somehow but when I held down option to start in OS9 instead of OSX ( OS( is on a different drive) I got the same thing briefly so I suppose something might be making a bad contact somewhere on the board. I really don't want to go inside until my G5 arrives in case I make things worse. My question is - is it perfectly OK to leave my machine on all the time - just set it to sleep overnight?