It seems like you have a loop in your network.
Verify that the PC is directly connected to the interface. Are you sure that the MAC is the pc's mac and not the switchport MAC? Did you get the mac-address from the pc ipconfig or from the show interfaces or show mac- command on the switch?
In most cases, this message is caused by ARP requests from the switch being flooded back to itself by a neighbor. Because the source MAC address is the system MAC address, a console message is logged and the packet is dropped.
Use the following command on all non-trunk ports:
-if#spanning-tree bpduguard enable
When the port receives a BPDU, it is put in the error-disabled state. Use show interface status command and check the log to see if any ports are disabled. This is typically used in conjunction with portfast to prevent loops.
http://www.cisco.com/en/US/docs/switches/lan/catalyst4000/release/note/OL_1983.html
https://www.cisco.com/en/US/docs/switches/lan/catalyst2970/software/release/12.1_11_ax/configuration/guide/swstpopt.html#wp1058660