I am running IOS version 4.7.2.O on a 3020 concentrator. It is being used by one access group that authenticates to a AD server and gets DHCP from there as well. The group is for local LAN access. All was fine until we updated to the 4.7.x code. Now when the first user initiates a connection the CPU spikes to 100% and locks the concentrator up. We have the SEP-E module and it is handling traffic according to the logs.