We have a Cisco Wireless Controller, model 4402 with both b/g and a/n. The AP's have the latest IOS. We have two SSID's available- one for the private network and one for a public network that provides only internet access. The DHCP server for both wireless networks runs off of the controller. We have a class B network for the private network and a super-netted class C, 500 ipaddresses for the public side. The problem is that over a few weeks Macbooks lose the ability to access the internet over the public network. They get a correct IP address, gateway and DNS server however, they are not able to ping anything on the network but can ping themselves. A Macbook could work today but then not tomorrow. We sort of resolve the issue by rebooting all of the AP's but would like to resolve the underlying issue. Any ideas?