The "system out of memory" error occurs after the filer clicks the submit button.
This error comes from the eFiling system and it is caused by the size of the document(s). Even though the submitted documents are under the maximum allowed, the system is not able to process them at the time the error occurs.
Since we have only noticed this error at peak times, it appears that the system is at times not capable of handling documents close to, but less than the maximum allowed.
The solution is to either reduce the document sizes or wait an hour or two until the eFiling volume falls.