Question : Problem: Kernel Panic - how to fix?

hi

i was using my mac book pro yesterday, installing some updates and i plugged in an external hard drive.  all of a sudden it shut down and now i get this when i boot up?

panic(cpu 0 caller 0x003AA827): Unable to find driver for this platform "ACPI".

Debugger called:
Backtrace, Format - Frame : Return Address (4 potential args on stack)
0xbe9bdf8 : 0x120d08 (0x3cb134 0xbe9be1c 0x131de5 0x0)
0xbe9be38 : 0x3aa827 (0x3ef700 0x25ed780 0xbe9be68 0x25f8600)
0xbe9be58 : 0x38c5c2 (0x26aa180 0x25d2c80 0x1 0x3bfb47)
0xbe9beb8 : 0x38de41 (0x25d2c80 0x26aa180 0x269e000 0x26a5620)
0xbe9bf38 : 0x38d6a9 (0x25d2c80 0x25f8600 0x0 0xffffffff)
0xbe9bf88 : 0x38edee (0x25d2c80 0x0 0x134c09 0x38ed14)
0xbe9bfc8 : 0x19ac1c (0x25f9e90 0x0 0x19e0b5 0x25ebb70) Backtrace terminated-invalid frame pointer 0x0

Kernel version:
Darwin Kernel Version 8.9.1: Thu Feb 22 20:55:00 PST 2007; root:xnu-792.18.15~1/RELEASE_I386

i ran the hardware test off the cd and it all passed.  I CANT wipe this because i have software that i cant lost (dont have cd's to reinstall)

someone please help! :(

Answer : Problem: Kernel Panic - how to fix?

Should not be a very big problem. This has, unfortunately,  been a little to common with recent updates done through the auto updater. From Panther though most of Tiger we could just leave auto update on and just click update  when available, click install, reboot, and no problemo. The real Apple recommended  approach to every update is to make sure that everything is backed up, fix permissions, install, reboot and fix permissions again. The ideal way to fix this is to either have another Mac from which to boot this machine through fire wire target mode or an external drive with a Mac OS  X installation. Once booted from either vantage point you can run various utilities on it to get it up and running again.  I  would recomend going right for the big guns and use Disk warrior 4 unless you are running Leopard cuz I don't think DW is updated yet for Leopard. If you running Tiger than DW will find out if you had any hidden directory errors which caused the meltdown(worst case scenario). Once you can get it to boot again on its own, you can fix permissions and download the manual update dmg from Apple and install that.  For whatever reason, the manual update completely replaces updated files. If you have no other way to boot the Mac externally then try booting it in Safe mode and or single user mode and run fsck. If it boots, then do the manual update reinstall.
http://homepage.mac.com/geerlingguy/mac_support/mac_help/pages/0009-fsck_su_disk_repair.html