What causing the Flapping between ports ?

Hi i have been recevied this message from two of my access ports. once i shut down one port (port 4) the flapping stop. Please help me determine what cause this problem and how i can solve it.
Below is the message from the flapping….

LAE_Switch#
Feb 17 12:48:20.079: %C4K_EBM-4-HOSTFLAPPING: Host 00:30:48:92:B9:6F in vlan 4 is flapping between port Gi1/4 and port Gi1/8
Feb 17 12:48:20.591: %C4K_EBM-4-HOSTFLAPPING: Host 00:30:48:92:11:65 in vlan 4 is flapping between port Gi1/8 and port Gi1/5
Feb 17 12:48:21.163: %C4K_EBM-4-HOSTFLAPPING: Host 00:23:37:00:08:5D in vlan 4 is flapping between port Gi1/4 and port Gi1/8

cheers