[PLUG] Broken root!

[John Jason Jordan]

I installed the final of Feisty amd64 Desktop on my new computer this
morning. Then I used the new computer to back up my Edgy amd64 laptop,
preparatory to doing an apt-get dist-upgrade on the laptop. Everything
was going fine on the new computer until I decided I wanted to install
more software. I clicked on System > Administration > Synaptic Package
Manager, expecting the little window for my root password to pop up.
Instead I got a window that said:

Failed to run /usr/sbin/synaptic as user root.
Unable to copy the user's Xauthorization file.

What happened? Root password was working before because I did the
backup as root with the cp command after mounting the laptop via nfs. I
copied everything to a folder I created on the new computer, ~/backups.
I can't understand how it would be possible, but could the backup have
goobered up the root account?