We were having a similar problem. Our problem turned out to be that we had included a broadcast address (x.x.x.0) as part of your IP address scope for a particular profile. Once the broadcast address was removed from the assigned IP address scope, the problem disappeared.
The problem here was also related to the IP pool but was slightly different. I could see in the Monitoring-Statictics-AddressPools that the first address of the pool was HELD, even though it was a valid address. I just removed the address from the pool, then add it back and the problem never came back.
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...
[toc:faq]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 and UDP are I...