I configured a router and had an outer security access-list put on an interface which denied certain criteria. This was put on after everything was checked during an on-site installation. Nearly 24 hrs later this error message came up as the monitorinbg software showed the vpn tunnel as down - Mar 31 14:02:53.572: %CRYPTO-4-RECVD_PKT_MAC_ERR: decrypt: mac verify failed for connection id=10. He applied this line to my access-list "permit ip any any". Why did this happen and why after 24 hrs?
I have this problem too.