From what I've gathered in researching this issue, this table was dropped in 2.5.

To see the error:
– Go to Grades
– Categories/Items --> Simple View
– Click on the "Edit Calculation for Course Total" icon
– Scroll to the bottom and click on "Add ID Numbers"

You get:
Error reading from database

More information about this error
Debug info: Table 'moodle2.mdl_attforblock' doesn't exist
SELECT cm.*, m.name, md.name AS modname
FROM mdl_course_modules cm
JOIN mdl_modules md ON md.id = cm.module
JOIN mdl_attforblock m ON m.id = cm.instance

WHERE m.id = ? AND md.name = ?
AND cm.course = ?
[array (
0 => '114',
1 => 'attforblock',
2 => '1433',
)]
Error code: dmlreadexception
Stack trace:

line 423 of /lib/dml/moodle_database.php: dml_read_exception thrown
line 1005 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1397 of /lib/dml/moodle_database.php: call to mysqli_native_moodle_database->get_records_sql()
line 1347 of /lib/datalib.php: call to moodle_database->get_record_sql()
line 86 of /grade/edit/tree/calculation.php: call to get_coursemodule_from_instance()

Thanks in advance for any assistance...