ARP Cache Poison - hundreds of notifications!!!

Hello

 

My Norton firewall (NIS 5 on OS X Lion) is reporting hundreds of ARP Cache Poison attempts and the MAC address is that of my husband's HTC Incredible 2 phone. Our router is pretty secure with WPA2 and a complex password, and filtered by MAC Address as well.  What should I do about this?  I see advice on other threads to ignore this, but not sure if that applies here.

 

Thanks

 

Jen