IMac G5 won't boot in normal and safe mode, but will from single-user mode

Question

Hello everyone,
I'm quite new here, so I try to do my best if you have a question.
Yesterday, someone nearby me had a iMac G5 (Powermac8,1), and he sayd, that the computer sometimes will boot, sometimes not.
I did test it, I thought it was running fine, but when I played some music in iTunes, it was stuck on 9 seconds, and crashed (with a kernel panic). The guy also sayd, that there was nothing important on the computer, so a clean install was fine.
Now, the problem is, that it will not boot in normal mode (without anything pressed on boot), also it won't in safe mode (shift-boot), but it will, when I enter single-user mode, mount the hard drive and exit from single-user mode so it will go futher on booting. Sometimes it will not, and immediately gives you a kernel panic in single-user mode, but it will 90 percent of the time.
Then you've got another problem: when it's running in the normal desktop from single-user mode, it'll be stuck after some time again. If I look into the Kernel Panic file created, most times it's because of Spotlight indexing, so I disabled that.
He also gave me the disks (Apple Hardware Test and Extra Applications, and iMac G5 Mac OS X Install Disks 1-3) that came with the Mac. He sayd that I could use them, but I think he didn't test out the SuperDrive, because when I insert a disk, it will try to read, but it will make 2 same sounds, and quits after 10 tries, when it will spit the cd out. Also normal (audio) disks.
Also, I must hurry with the commands for mounting and exiting in single-user mode, or it will just not boot.
In all cases, after 30-45 seconds from pressing the power button, the fan will start blowing at full speed, and it will stop after the exit command in Single-user mode. That's weird.
I can't do anything with the SuperDrive, I can't normally boot in Mac OS X except for Single-user mode (but I don't think he would like to do that every time the computer boots up), and I have very limited time when Mac OS X arrived on the desktop.
When booting in Verbose mode, it will be stuck on this:
AppleSMU::PMU vers = 0x000d004c, SPU vers = 0x15, SDB vers = 0x01,
(and sometimes ends with a kernel crash by fsck_hfs)
Things I've tried (without any success):
- /sbin/fsck -fy (in single-user mode)
- Disabling Spotlight and mds
If you want some more information, feel free to ask!
Greetings
-MrYoranimo
PS: My main language is Dutch, so my English can be bad at some points.

Answer 1

Thank you for your support! This reply is a little bit late, because I was to the camping this weekend.
The only thing I sure do know, is that the iMac has a bad SuperDrive. That's one problem, but I don't really wanna use it, and you fix everything by Single-user mode and when I get to the desktop to test things and change stuff in the Preference Panes.
What also came to my mind was that there also is a problem with the videocard (driver), because sometimes when I boot into Single-user mode, I can see some white pixels which aren't supposed to be there. And when booting from SUM you can see that some of the colors are different and there are weird patterns on the screen.
I also tried to setup a NetBoot server on this computer (MacBook Mid 2010) with just Lion 10.7.4 on it, but I'm not that expert and I didn't really find the good posts on the Internet, although I tried it with the Server applications and both Server applications and DeployStudio. But I didn't succeed.
I don't really like buying a new FireWire hard disk or external FireWire dvd reader/writer, except if it has USB support, because my MacBook doesn't support FireWire, and I really wanna make use of it then.
If I know more or have fixed it, I will surely post again here with what I did to fix it (if no one else has posted here already ).