I recently moved from a pix 515 to an ASA5520 and have been having issues. Some issues I have solved some I have asked help for here. I currently have an issue with one of my vpn tunnels where during certain times of the day the tunnel seems to time out or reset and when this happens the files that are being copied over are truncated. There is no specific time it is totally random. This tunnel is between my main site and my off site they both have the same ISP. I have allowed traffic to go through with out nat on both firewalls. Main site firewall is an ASA 5520 and the offsite is a pix 515E. Here are some messeages from my syslog server. These are the main messages I am getting and are at different times through out the day.
Deny TCP (no connection) from 192.168.11.66/445 to 192.168.31.110/2015 flags ACK on interface inside
Teardown TCP connection 3696820 for outside:192.168.31.110/2624 to inside:192.168.11.66/139 duration 0:00:00 bytes 0 TCP Reset-O
Teardown TCP connection 3672791 for outside:192.168.31.110/2264 to inside:192.168.11.66/445 duration 2:45:27 bytes 176007536 Connection timeout
Teardown TCP connection 3693600 for outside:192.168.31.110/2562 to inside:192.168.11.66/445 duration 1:22:02 bytes 58006428 Connection timeout
Teardown TCP connection 3696973 for outside:192.168.31.110/2625 to inside:192.168.11.66/445 duration 17:56:01 bytes 262101592 Connection timeout