I'm trying to fix a hard drive problem for a friend. It's a HP Pavilion 6600 series (6636 IIRC). I've tried many different boot discs and disks. All but two result in a complete system lockup. The two that work are tomsrtbt and PuppyLinux. My Slackware 10.1 install CD and Knoppix 3.7 both give the "Passed an undefined mode number" error. When I press space or wait 30 seconds it freezes. TuffTest Pro hangs while it flashes "LOADING" during startup. My Win98 startup disk shows the same thing as the hard drive itself, a blinking cursor at the topleft corner, immediately after POST.

I finally moved the hard drive into a different box and viola, any bootdisk I throw at it loads. I was able to conclude that the hdd has read errors at the beginning and that's probably why the installed XP won't boot.

My question is, why does Slackware and Knoppix hang on th HP box after the error message? I tried Slackware with bare.i and Knoppix in both normal and failsafe modes.

Sounds like dodgy hardware to me. You really can't predict what will happen in that case. I'd suggest running memtest86 on the HP system -- oftentimes bad RAM is the culprit.

Thanks for the reply. I figured it would be a hardware issue. I will try memtest, if the disc will boot. If not I can try swapping the RAM stick with a known good one.

It booted my discs this morning. The two hard drives on the primary channel were disconnected from previous experimenting. Without them, or with just one, connected it'll boot from cds. Closer inspection reveals the power supply is only rated for 100W output, so I guess it's a power issue. The box has 3 hard drives, one CD-RW, one floppy, a sound card and a NIC.

I got what I needed from it: I verified the hda has bad sectors at the beginning and was able to mount it using Knoppix to backup the Docs and Settings folder.

"You really can't predict what will happen in that case." - One thing that IS predictable is disc damage. I never liked the way the case is designed. The back sits lower than the front so nothing is level.