Paypal Frustrations?

So Paypal IPN processing seems inconsistent. It's reasonably frequent that we're having transactions that are valid, but for whatever reason the order either stays "Open" for us or it ends up in "Incompleted".

I added some logging into and we are getting 'VERIFIED' as a response but I suppose something is not happening in fn_process_paypal_ipn().

Has anyone else run into this issue? It's relatively low frequency but it creates a lot of overhead for our order processing.