Um...your 7.87 GB startup drive only has 211.9 MB free?
EEEEK. I think we've nailed the problem!
Generally, the recommendation is for a minimum of
5 GB free when running OS X - that's for swap space etc. (The 10-15% you sometimes see quoted is mythical from what I've been able to deduce, especially as drive size has gotten so much larger in the past few years!) You're actually lucky you're able to do anything, but PLEASE stop trying to shut it down by using the power button; at this point, the potential for disk corruption may be substantial and not at all helped by essentially crashing the machine.
What to do? Well, if it were my machine/hard drive, I'd install a fresh copy of the OS to the other drive, start up from that, and then use Migration Assistant to copy all your files, applications and settings. I don't think you'll get SuperDuper to work with so little space no matter what you do. And David, I'd give some serious consideration to investing in a bigger HD if you're thinking you'll be using this G4 for any length of time. Hard drives are dirt cheap these days and even 16 GB is cutting it pretty fine. Heck, some people have 16GB of RAM these days! I know you're thinking of getting a Mac Pro, so perhaps you don't want to spend anything on this G4, but you could perhaps get an external drive, or an external case with an SATA drive that you assemble yourself (often cheaper) and then you have the option of sticking it in the new Mac Pro later (or continuing to use it as an external drive). ATA drives like those found in the G4 won't work in the MacPro. An external drive may have either type, but if you ever want to swap drives in or out of the case in the future, stick to SATA. BTW - the Mac Pros have FOUR internal hard drive bays.
(Yes, mine are all filled...)
