Quicktime disaster leads to SystemUIServer crash.

[EReilly]

Hi. Long story short:

1. I tried running Software Update on totally full hard drive, ended up with a blinking question mark screen at startup
2. I brought the computer to the Apple store and got my OS running again.
3. However, Compressor and my Quicktime Pro codecs were now inoperable. I tried downgrading Quicktime from 7.3.1 to 7.2 using Pacifist.
4. Now my Menu Bar is missing and the Console indicates that SystemUIServer is repeatedly crashing. Almost all of my apps now refuse to open.
5. I can't find my OS X cd.

I've tried trashing all the prefs with no luck. I've repaired privilages and run fsck in single-user mode. I can't get into safe mode for some reason. I can't create a new user account because I can't get into System Preferences. What should I do?