The line you mentioned looks like this:
$data['checks'] = Mage_Payment_Model_Method_Abstract::CHECK_USE_CHECKOUT
This means Magento cannot find the constant CHECK_USE_CHECKOUT
in the class Mage_Payment_Model_Method_Abstract
.
if your code is up to date, the constant should be there.
The constant was introduced in Magento 1.8.
The fact that this does not work for you makes me speculate, that at one point, you had an older version of magento (1.7 or below), you had to do some changes in the Mage_Payment_Model_Method_Abstract
and you (or someone else) copied that class to app/code/local/Mage/Payment/Model/Method/Abstract.php
.
Because of this, the class in the local
folder is used and it's not up to date.
I suggest checking the differences between the class in the local
folder and the core one from the version you previously had, copy the class from core
to local
(from the new version) and implement the changes in the new class.
Note: This is what can happen when you copy code to local
code pool and you later upgrade.