Having created a managed package which is deployed in a customer's org, we are running into an error that results in the processing stalling and never finishing. 

Details : 
-34 Batches are queued, processing of the first appears to complete (dml associated with it seems to happen)
-Debug logs seem to indicate that the second batch is processing, but dml does not occur (though it says it does in logs)
-In Apex Jobs, we perpetually see the job as processing the first batch. After many hours it seems to resolve, usually as a Internal Salesforce.com Error.
-We received the " Unable to retrieve file from ACS, transient error?" error by email for this once. 
-There appear to be other processes in this org (triggers in managed packages) that may be put to work as a result of inserts/updates from our batch processes.
-The code itself is making some callouts, processing the response, and inserting/updating records in salesforce. This code/package has not experienced this issue in any other orgs. 
-The particular response being processed for this customer does not appear anomalous in anyway. 
- It ALWAYS stalls in the same way, processing the first batch then not completing the second or continuing after that

Seeing some old results on this error indicating this was an issue particular to na7 a number of years ago. This instance is na9, and they tell me that it is now 2016. 

Opened up a case with Salesforce, to no avail; a lack of premier support resulted in their suggestion to make this post. 

I appreciate your help. Thanks.