Comment 21 for bug 528203

@Dany

Finally got it working again.

1) Browse to ~/.local/share/ubuntuone/ and delete the syncdaemon folder. I'm not sure if you have to kill the ubuntuone processes before you do this.

2) Go to System > Preferences > Ubuntu One

3) Log in as usual

4) If it asks for access to the key-ring, allow it (once or always, your choice). It should now completely again.

5) If it did not ask for access to the key-ring, and instead goes right to your files in the web-interface, go back to step 1.

I had to do this 3 times before it worked.

Got this from http://ubuntuforums.org/showthread.php?t=1291576&page=5