Hello,
I have a Magento 1.7.0.2 installation patched with available patches. I noticed the below lines in /var/log/system; almost 1 line like this per 2-3 seconds is recorded in the /var/log/system file:
ERR (3): Notice: Trying to get property of non-object in /app/code/core/Mage/Core/Model/Config.php on line 1245
The problem started after I installed a purchased extension.
