> I somehow managed to delete /etc/passwd, and now can't log in. I tried 
> recreating it by booting from the IDE installation CD and copying /etc/passwd 
> from there to the hard drive /etc, but it doesn't seem to work; it appears 
> that passwd is somehow protected by hidden features in the file system. Is 
> there any way to bring this system back so that I can log in?

When you say you copied it and it doesn't work - what does this mean? Does the file appear or not?

Maybe you have deleted other files, e.g. /etc/shadow.

The QNX docs have a chapter "Managing User accounts", which includes a section "Forgot your password?" which has a few 
suggestions on what else you could do:

http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=/com.qnx.doc.neutrino_user_guide/accounts.html

Good luck!

- Malte