Comment 3 for bug 991354

Hi Stephen

Thanks for taking the time to report this bug in Ubuntu.

Looks like something has left some .lock files in place on the files used for user management. This does happen from time-to-time.

Have a look in /etc/ for any files ending in *.lock and remove them if they are present - the following should be safe to remove:

   passwd.lock
   shadow.lock
   group.lock

Thanks