I've got a subtle problem with a Cisco router terminating about 15 VPNs. In some cases any tunnel stop working but phase 1 is up and I can see also one SA on phase 2 with 0 packet encrypted or decrypted. Encyption domain acl has no matches.
On the other side phase 2 SA has only packets encrypted but no return traffic; the enc dom ACL are the same and usually the remote vpn gateway is a PIX.
Do you have any idea (except reboot)? My device is a Cisco 2851 with the following IOS version
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version12.4(1a), RELEASE SOFTWARE (fc2)
Best regards Marco Canova