OK, this one's a doozy. I've run into a problem with my 12" G4 1.42 Ghz iBook that seems a. unprecedented - no reports on the web of this combination of symptoms that I can find and b. pretty much inexplicable. So any help would be much appreciated. Bottom line, the machine is incapable of booting into a usable state. I came into my bedroom yesterday morning to find it displaying the infamous "You need to restart your computer" message, indicative of a kernel panic. So far, so reboot. Unfortunately, the machine had barely hit the desktop when the same thing happened again. And again. And again and again. Once or twice I got to the stage where it had almost finished booting (time, airport status, etc. appearing on the desktop menu bar). Once I even manage to get Firefox to load up... for about three seconds. Sometimes it unpredictably boots into open firmware ("Illegal execution request" or somesuch, but the messages are inconsistent). A 'mac-boot' command will lead to the 'no system disc' screen (flashing question mark folder). Yet the iBook will always happily pop into Target Disk Mode on startup, so I don't think there's anything wrong with the drive itself. Most often, it didn't even get to the desktop. The progress bar starts... then freezes. There's a kernel panic before the thing's even finished booting. I should say that, although I've recently subscribed to a new ISP and (phew) bought a new Mac Mini, there have been no substantive changes to the iBook (i.e. software installations or hardware alterations/additions) recently. Indeed, as will become clear, even if there had been, I've since undone them. Note: the optical drive failed earlier in the year, and I've not had to moolah to replace it. Hence the DW and install described below were done from the Mini in Target Disk Mode. Failed approaches to the problem have thus far included, in order: 1. Zapping the PRAM. 2. Zapping the PMU. 3. Disk utility. Some repairs to permissions made. 3. Throwing Disk Warrior at it. It found a few "minor" problems and rebuilt the registry. After this, the iBook achieved the hitherto unheard-of almost-loading-Firefox mentioned earlier. Actually, it connected to my wireless network just long enough to get the date and time from the nntp server before falling over. Or that's what I'm guessing it did, because it suddenly knew the date and time that had earlier been erased by resetting the PMU. Although, having said that, on a couple of occasions it subsequently responded to the power button being pressed by racing the fan for a few seconds, making an odd beep (like no noise I've heard from a Mac before) and flashing the sleep light like it was trying to induce an epileptic fit. The flashing sleep light is apparently a sign of a PMU in dire need of a reset, so I did. Again. 4. Remote 10.4 install from the mini via firewire. Not a clean system reinstall, but archive. When this failed to work, I became worried. 5. Perhaps a little late in the day, I went for a hardware test. Which it passed with flying colours. Damn. 6. Having backed everything up, the last resort: clean system reinstall. Nothing in the world can stop me now! Bzzzt. Now it just gets to the 'Welcome to OSX' all-singin' and dancin' demo... and demands I restart. 7. It has a 3rd party 1Gb SO-DIMM. This is not loose, and the problem is replicable (indeed, unavoidable) even when the DIMM is removed. So, it passes a hardware test, has had a clean system reinstall and should, to all intents and purposes, be 'as new outta-the-box' (apart from the extra memory and the optical drive being munted, obviously). But it isn't. So, have I missed anything? Any and all suggestions gratefully received. Many thanks!