Crippling, horrifying system problems

Question

A couple weeks ago, while using my Power Mac G4 (10.3.9), I noticed open applications becoming unexpectedly unresponsive. Attempts to force quit would result in everything from the Finder to the Dock becoming unresponsive. The color wheel spins perpetually, but the menu clock & system don't freeze, unless prompted to by frantic clicking. As days passed, the problem became more frequent. It started freezing during every few start ups, sometimes at the Apple screen, sometimes at the blue screen, sometimes after the dock and desktop picture had loaded.
The hangs were so random that I couldn't narrow it down at all, not even with the Activities Manager. There's nothing in the CrashReporter because nothing ever officially "crashed," and everything in the system.log that looked suspicious to my untrained eye turned out to be normal. I've turned off Classic and moved the fonts out of Classic's Font folder. The start up disk passed verification, and I repaired permissions. I've logged in under a fresh user name, and it still won't behave. Even in Safe Mode, it locked up.
Occationally when I would reboot, the flashing question mark folder would appear & currently the only bootable system is OS X. When I tried reinstalling 9.2.1, it stopped and told me to do something with the "battery recondition" file, which I couldn't find. (Also, it won't boot from my Sys 9.0 boot CD.) Then I tried reinstalling 10.3 (from the official discs). I told it to put the old system in a folder named "Previous System" and started the install, but an error occurred. Now, I can only boot off of the Install CD & neither of my 2 internal hard drives appear in the Installer or Disk Utility!!!
Around the time that the problems started, I had booted up in OS 9 to use a USB floppy drive. OS 9 said that the computer hadn't been shut down properly (which wasn't true) and after verifying the hard drive, it said I needed to back up and repair the disk. But it's said that before when I've booted in 9 in the past. Even my 10.2 iBook G3 says that & it's still running just fine.
Also, the G4 has a USB PCI card that crashes the computer when it goes to sleep, so we keep the system & hard disk awake constantly. If I could find my hard drive and get the system functioning for at least 10 minutes, I would gladly run every hardware test available.
If anyone knows anything that might get me out of this mess, I would be eternally grateful. I'm really starting to panic now.
Thanks!
Samara
Quicksilver G4 733Mhz   Mac OS X (10.3.9)  

Answer 1

For information's sake, here's what I've found out.
The hard drives don't show up at all now. Trying to boot up from them causes a kernel panic with IOATABlockStorage and IOATAFamily stuff in the backtrace. The hardware test came up with a mass storage error of ata1/6/-1. Apparently, the ATA bus for the internal hard drives is "worn out," according to this article:
http://www.macosxhints.com/article.php?story=20050831222635526
The solution, which I have yet to try, is connecting the hard drives to the optical drive's bus, or just getting a PCI card to replace the bus.