I just found another possibility:
So you cannot get to single user mode... can you get to open firmware, and reset the non-volatile RAM?
Cmd-Opt-O-F at boot
(each line exactly as shown, followed by <return>)
I'm now able to repair the volumes. Waiting for it to finish and reboot.
AHA! no wonder it doesn't boot using c key, yiou have setup...
Firmware password protection in Mac OS X ...
It would block usage of all the startup keys, like C, N, T, D, CMD+s, CMD+Option+p+r, CMD +v, Option boot will show a lock, and Shift, as well as booting from anything but the Hard Drive.
Force Removing Password Protection
1) Add or remove DIMMs to change the total amount of RAM in the computer.
2) Then, the PRAM must be reset 3 times. (Command + Option + P + R).
Thanks for your quick response and help.
I was able to repair the disk and permissions on all volumes. On reboot I logged in using my password. No desktop or dock. Got a message that "The application Spotlight quit unexpectedly." Relaunch is blue but I can't click to try the Relaunch. Ignore and Report is unresponsive.
Setting firmware password protection is news to me. I'd have no reason to do that. Not even sure I could do it accidentally.
I'll will try your solution.
I repeated Repair Disk and Repair permissions for the volume I like to login.
(Command + Option + O + F)
2) Type "setenv security-mode none" and press return.
3) Enter in the password at the password request prompt and press return.
4) Then type "reset-all" to restart the computer.
Removed two DIMMs
This time Reset PRAM worked. (ran 3 times)
I log into my preferred volume and -- no desktop and no dock.
This time Option works and I chose another volume.
No problem! Logged into that volume without hitch.