Magento Layout error

Magento Layout error

We have a Magento module that works fine in more of 50 stores and was fine
also in this particular store... but after update in one of them... is not
more loading the templates, the controllers are called, work fine, but the
page don't show up, this problem happens only with the module, the other
templates of the site, work fine... putting the store to show the erros,
this is one clue
Recoverable Error: Object of class Mage_Core_Block_Template could not be
converted to string
also we putted a log in Mage_Core_Model_Layout_Update and many erros like
below show up..
2013-09-11T20:54:04+00:00 ERR (3): Recoverable Error: Object of class
Mage_Adminhtml_Block_Page could not be converted to string in
/home/toyshow/www/app/code/core/Mage/Core/functions.php on line 110
2013-09-11T20:54:04+00:00 ERR (3): Notice: Object of class
Mage_Adminhtml_Block_Page to string conversion in
/home/toyshow/www/app/code/core/Mage/Core/functions.php on line 110
2013-09-11T20:54:04+00:00 ERR (3): Recoverable Error: Object of class
Mage_Adminhtml_Block_Page could not be converted to string in
/home/toyshow/www/app/code/core/Mage/Core/Model/Layout.php on line 460
Had have somene a similar problem?