Major Permissions Problem

I have a buddy running a PowerBook G4 with 10.5.x. It's been going great. However - oh, and let's not dwell on this - she decided to "make her computer more secure" and in doing so she changed permissions on her computer and then restarted. She told me that she did "get info" and changed permissions on "Other" to nothing. I'm not sure what she changed them on, exactly, but I'm pretty sure she had the icon for her hard drive selected. So, she made it so Other couldn't access her whole drive. I'm not 100% sure, but from what she says and what I'm seeing, I think that's what happened.

I booted the machine in target mode and it wouldn't even show up on another mac. Ok, so...

I booted to SUM. First I tried to run applejack, knowing it would fail on the permissions step. The drive check.repair went well. Everything checked out. There were a few minor problems. But, as expected, permissions repair would't run - more specifically, it ran, but it said everything was off limits.

So, I booted to SUM again. I did sbin/fsck -fy - once again, everything was fine. So, I ran sudo chmod -R 755 / and this is what I got:

sudo: can't open /private/etc/sudoers: Permission denied

root# sendmail: warning: valid_hostname: empty hostname

sendmail: fatal: unable to use my own hostname

Sudo is having an identity crisis.

So, what is going on? Will I have better luck if I take the drive out and put it in a carriage?

Oh, wait... at one point I ran the chmod command without sudo, and it started to run through every single file on the drive, which pleased me at first. I thought, "Great, it can see all the files so everything is there. And it's changing things to make them usable." But then I noticed that only the first half was true, for after every file it said, "Read-only file system".

So... thoughts?