Disk utility, spotlight, software update... none are working.

Question

A mix of problems have developed lately. I assume they're connected, although perhaps not.
1) I can't repair permissions. It begins properly, then goes forever and forever until I quit (or force quit) Onyx.
2) Disk Utility won't, er, activate? I open it, and then it's "Gathering Disk Information" forever. ("Forever" = several hours). It never reads any of the disks, so I can't repair permissions that way, or do any of the Disk Utility functions. This happens whether I start Disk Utility from my main hard drive, from a backup clone, or from the Tiger startup disk. It doesn't fail--it just keeps going.
3) Software update begins when I ask it to, the blue bar scrolls along, and then it goes no further. No crashing, no completion, just quietly musing away.
4) Spotlight can't find anything: "No results found" for everything. I see others have this problem, so maybe it's not connected.
5) I've tried to reinstall Tiger from the startup disk, but I can't do that either: I click on Agree, then the computer starts "Selecting Destination", and all the different drives are there, but grayed out--and the computer just keeps thinking, with the little wheel spinning.
For all of the above, Activity Monitor doesn't indicate a freeze--they all need 2-3% of the processor, and there's no memory leak or anything.
I'm very confused about my hard drive clone (on a 350GB external SeaGate). I have the same problems when I boot through that drive, which suggests this isn't a hardware problem. Or at least, not a disk problem. A processor one? Oh, what do I know... I'm way out of my depth here.
However, all applications seem to be working properly!
I'm not too sure about the history of these problems. I'd been having iTunes library problems for a while that may have been hiding these issues from me; I certainly started noticing these problems in the past 2-3 weeks, so the connection to 10.4.11 probably isn't coincidental.
Any help would be really appreciated. The PowerBook G4 is getting a little old, but I'm hoping to hold off on a new computer for a while yet. Thanks!

Answer 1

I APPEAR to have resolved the problem (I hadn't posted yet because things only got sorted out yesterday, so I'm not certain this is done with yet).
What I did: I turned off Sleep Mode and kept the computer on all night. I presume this let the daily maintenance script run--it's set to run at 3am, I think. (I'm not sure if I ever tried to run the scripts alone through Onyx; I don't think I did--I think I just tried to run a big batch of operations, which was foolish of me.)
The next morning, things still weren't right--no Spotlight, for example--but I was able to open Disk Utility, which I hadn't been before. That let me Verify Disk, repair permissions, and so on. For the rest of the morning I kept repeating things again and again--Disk Utility and (unneeded) disk repair from Tiger start-up disk, complete clean-up through Onyx, etc--and each time more functionality seemed to come back. There were steps backwards--Disk Utility wouldn't open again for a bit--but something else was working, and with another reboot, it'd be back. I can't remember the order I did this in, but I also made sure to run, individually, each of the maintenance scripts (through Onyx).
Eventually everything seemed to be back in order. A day and a half later, and all things still seem to be OK.
Curiously, through all of the clean-up/ mop-up--actually, through ALL of this mess--there were never any error messages. No spinning pizzas, no freezes; just blue bars and "clockhand circles" (what are those called?!) that never ever finished.
So, I suggest either making sure the computer is on all night, or running the daily maintenance script (you can run it through Onyx, and presumably other ways that I don't know about).
A moral of the story: those maintenance scripts appear to have solved the problem, whereas repairing permissions didn't.
(I find it oddly amusing that, out of all the things I tried to do, the one that finally succeeded was just leaving the computer on and letting it take care of itself.)