Hi to everybody. I apologize first because I do not know if this is the right section for my problem, but I could not find anything more suitable.

I have an Asus 900 with Ubuntu Netbook Remix 10:04 In a nutshell: I realized today, trying to install a new program with Ubuntu Software Center, that I can not anymore authenticate myself as root. Of course I have not changed the password, but the old one is not anymore accepted ("Authentication failed").

The interesting thing is that I can install programs without problems (using the same old password) with the package manager in Administrative Tools (synaptic). Here, the authentication works well.


Opening a terminal, I can use sudo to run any command by providing my password, with no problem at all. Following some guides found on the web, I reset the root password (supplying the same one as before) and everything went well. Only .... nothing has changed! Ubuntu center software authentication always fails.

What could have happened? Maybe I did some mistake by editing /etc/sudoers to solve another problem some days ago. Ubuntu told me that my username was not in the sudoers file, so I resolved it by adding to /etc/sudoers the line
myusername ALL = (ALL) ALL

I checked the contents of the file and, apart from this line added, it is as it was before (I compared with that on another PC with Ubuntu).

Can anyone make some sense out of it? Starting from the fact that the package manager does function ... but software center does not... I am puzzled!

Thanks in advance for your patience and kindness!

So did you enable the root account in Ubuntu, even though this is explicitly not recommended in Ubuntu?? If so, and if you have been running the system as root, then this is likely part of your problem.
Have you been running the system as root?
Well, this is a possibility also.
In the future, please forget about enabling the root account in Ubuntu. There is no need to do that. I have been using Ubuntu for 5 years, and I have never found it necessary or beneficial in any way to enable the root account.
Use sudo from now on. See this if you can no longer use sudo:
http://www.psychocats.net/ubuntu/fixsudo

Solved! The solution was resetting root's password, booting in recovery mode. I simply re-entered my previous superuser password, which was (I don't know why and how) deleted. Now everything is ok.

Thank you very much for helping!