CRM/Core/Payment.php can't find disable payment processor

I was able to replicate this on a fresh 3.3.5 install (can only find 3.3.6 in listed versions here), though using the live database. I believe this issue could crop up on any install if a previously used payment processor is turned off. It appears that it CRM/Core/Payment.php is still looking for it but can't find it if it's disabled.

On the membership tab:

Fatal error: require_once(): Failed opening required 'CRM/Core/.php' (include_path='/var/www/vhosts/dev.freeform.ca/bikeunion/sites/default/civicrm_custom_php:.:/var/www/vhosts/dev.freeform.ca/bikeunion/sites/all/modules/civicrm/:/var/www/vhosts/dev.freeform.ca/bikeunion/sites/all/modules/civicrm//packages:.:') in /var/www/vhosts/dev.freeform.ca/bikeunion/sites/all/modules/civicrm/CRM/Core/Payment.php on line 103

On the Find Membership when choosing "Grace" or "Pending":

Fatal error: require_once(): Failed opening required 'CRM/Core/.php' (include_path='/var/www/vhosts/dev.freeform.ca/bikeunion/sites/default/civicrm_custom_php:.:/var/www/vhosts/dev.freeform.ca/bikeunion/sites/all/modules/civicrm/:/var/www/vhosts/dev.freeform.ca/bikeunion/sites/all/modules/civicrm//packages:.:') in /var/www/vhosts/dev.freeform.ca/bikeunion/sites/all/modules/civicrm/CRM/Core/Payment.php on line 103

On line 103 of CRM/Core/Payment.php it tries to include the payment processor:

require_once( str_replace( '_', DIRECTORY_SEPARATOR , $paymentClass ) . '.php' );

I'm not sure why the member tabs or Find Members need to include the payment processor, but it seems to be looking for it. The error disappears when I enable the previously disabled processor. That processor had been used in the past.

I realized that I had turned off some payment processors