error in "Login or create a new account"

Hi
I get the following falat error:
Object of class stdClass could not be converted to string in /mounted-storage/home143/sub028/sc76855-CMTT/agrilob.com/daphna/templates/yougrids/yjsgcore/yjsg_core.php on line 18
It happens both on Joomla 1.5 and 1.6
As you see I am using yougrids template.
Can anyone help?
I am attaching the file where the problem happened, maybe this can help

Thanks for any help
Daphna Levin