Not sure if this is the correct forum since it involves Pix515e units. I have 2 Pix 515e f/w setup as failover pair. One day, internet was dragging, pages loading poorly.
Checked the 4006 log and it said, "Host 00:12:80:34:94:E1 in vlan 1 is flapping between port Fa4/2 and port Fa4/3."
4/2 is the primary Pix and 4/3 is the failover unit. I shut down the failover and things got back to normal. The 93:E1 is inside interface.
Could the flapping be caused by a bad NIC in the primary Pix? This happened once before in March.