I have been running a L2TP over IPSEC VPN for awhile now with no problems. For some reason it mysteriously stopped working at 6:45pm CST yesterday. Posted below is the debug log for crypto isakmp and ipsec. Attached is the debug output. 71.40.x.x is the ip address of remote office where the machines remoting in using windows vpn client. 72.5.x.x will equal where the cisco asa 5520 resides.