I have the same problem I installed joomla 2.5.9 and the component CB 1.9 when I update profile in the frontend "Contact Info" the user table field params get like this:
{"0":"{\"admin_style\"
"\",\"admin_language\"
"\",\"language\"
"\",\"editor\"
"\",\"helpsite\"
"\",\"timezone\"
"\"}"}
But if I update in the backend the params field come back to :{"admin_style":"","admin_language":"","language":"","editor":"","helpsite":"","timezone":""}
There is something that I can configure or it's a bug?