Password change

[FeMike]

the wiki page says the username change is "usermod -l NewUser -d /home/NewUser -m rock" but when I go into root I am unable to change anything I am getting "user rock is currently used by process 738 or invalid option -1      

I'm still new to this so forgive me if my help is not useful. When you went to change user name were you already logged into rock and then switched to root to do the change? If so try powering down and restart but this time log into root first then try to change. I wonder if that process was already running when you switched to root.

Edit:
Previous poster beat me on the reply and more well versed then mine. Go with that.