Found it. The App is called Store Configuration Monitor and it has a bug in its helper functions. In admin/includes/functions/general.php change the two functions to
function tep_configuration_update($cID, $configuration_value) {
$configuration_values_query = tep_db_query("select configuration_value, configuration_title, configuration_description from configuration where configuration_id = '" . (int)$cID . "'");
$configuration_values = tep_db_fetch_array($configuration_values_query);
tep_db_query("insert into configuration_changes (change_date,previous_setting,new_setting,change_title,change_description) values (now(),'". tep_db_input(tep_db_prepare_input($configuration_values['configuration_value'])) ."','". tep_db_input(tep_db_prepare_input($configuration_value)) ."','". tep_db_input(tep_db_prepare_input($configuration_values['configuration_title'])) ."','". tep_db_input(tep_db_prepare_input($configuration_values['configuration_description']))."')");
// Check to see if the configuration value changed is the Store Owner's Email address - if it is send a configuration change notification to the existing Email address on file.
if($cID == 3) {
tep_mail(STORE_OWNER, $configuration_values['configuration_value'], EMAIL_CONFIGURATION_CHANGE_TEXT_SUBJECT, EMAIL_CONFIGURATION_CHANGE_TEXT_BODY, STORE_OWNER, $configuration_values['configuration_value']);
}
tep_mail(STORE_OWNER, STORE_OWNER_EMAIL_ADDRESS, EMAIL_CONFIGURATION_CHANGE_TEXT_SUBJECT, EMAIL_CONFIGURATION_CHANGE_TEXT_BODY, STORE_OWNER, STORE_OWNER_EMAIL_ADDRESS);
}
function tep_module_change($action, $class) {
tep_db_query("insert into configuration_changes (change_date,previous_setting,new_setting,change_title,change_description) values (now(),'','". tep_db_input(tep_db_prepare_input($action)) ."','". tep_db_input(tep_db_prepare_input($class)) ."','')");
tep_mail(STORE_OWNER, STORE_OWNER_EMAIL_ADDRESS, EMAIL_CONFIGURATION_CHANGE_TEXT_SUBJECT, EMAIL_CONFIGURATION_CHANGE_TEXT_BODY, STORE_OWNER, STORE_OWNER_EMAIL_ADDRESS);
}
Then you should be able to update values normally in admin.