Eventhough the syslog error messages suggest that it might be a memory issue, I would recommend that you open a TAC case to get the memory depletion issue checked/confirmed to see which particular process is causing the issue. Memory on ASA is preallocated per block, and some processes might be sharing the same block.
If you check "show failover" output, there might be few errors due to the error messages as the stateful failover is not able to allocated the xlate slot record.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...