Comment 2 for bug 530063

diego,
sorry you are having problems with Ubuntu One. It looks like you are affected by bug 498444. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug ( I have posted the workaround below). Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

WORKAROUND:
Start Ubuntu One client if it is not already running (Applications > Internet > Ubuntu One) open the Preferences panel by right-clicking the Ubuntu One applet in the top panel and select Preferences. Set the 'Connect on Start' to 'Never'. Then when you wish to sync you will open Ubuntu One manually (Applications > Internet > Ubuntu One) left-click on the applet and select 'Connect'. Sorry for this inconvenience. This workaround is only temporary as the Ubuntu One Team is working very hard to resolve this issue.

NOTE: Another way to resolve this issue is editing the file ~/.config/ubuntuone/ubuntuone-client.conf directly (Ctrl + H to view hidden .config directory in your Home folder). Changing the 'connect' value to '2'
EX:
connect = 2