After upgrading from 12.04 to 12.10 I got all entries of Online Accounts blank. See the screenshot:

I tried to uninstall gnome-control-center-signon and install it back, but no luck. Is there any way to fix it or at least clear all the entries so I can add them again? By the way, I cannot add new entries as well, because the option list for account type is also empty.
Please help. Thanks.