Persistent Kernel Panics During Boot

Hey guys,
I've been running 10.6.4 on a model ZG5 for several months now without any problems, using NetbookInstaller 0.8.4 RC1. As far as I know, I have not done anything recently that would deeply affect my system, just general web-surfing and word processing. However, yesterday after a reboot my trackpad and keyboard would not work. Another reboot fixed that, but ever since then I have been getting Kernel Panics (the kind without debug information in the background) sometimes while booting up. The problem seems to have gotten worse, since it now happens virtually every time that I try to boot.

I've tried just about everything I can think of to find out what the problem is. Repaired the permissions, repaired two minor errors with disk utility, ran NetbookInstaller, reapplied the latest combo update and ran NetbookInstaller, ran TechTool without finding any errors or bad blocks, etc. The only thing that works is using chameleon's recovery=y to boot up, but that's inconvenient. Once I do manage to boot up, everything seems to run fine.

I have a time machine backup, but I misplaced my install USB stick and I have not had any luck booting from an external HD with a NBM-patched installer. It just kernal panics too.
Any help would be appreciated. Thanks