So, I'm trying to boot in single user mode on an Intel based 20" iMac on a network. For some reason, I'm unable to use single user mode. Is it possible for a network administrator to block access to single user mode? Or, is it only administrators who can boot in single user mode? Or am I just not pressing the button at the correct time...? Maybe that's the problem. If anyone knows EXACTLY when in the startup process I need to start holding cmnd-s, please enlighten me.