通过DHCP无法获得有效IP地址

最近在客户那里连接他们的无线网总是在电脑（windows 7 enterprise, sp1）启动后第一次无法通过DHCP获得有效IP地址。或者重新再启动一次电脑，或者手动关掉WLAN开关重新打开，才能获得一个有效的IP地址。DHCP server那边一直是正常工作的。查看本地的日志，发现有Eventid为52003的错误：
An error occurred when DHPQEC tried to renew DHCP lease in the adapter {f1edc5b3-d9dc-4147-ae27-815bf44f8356}. Error code is 0x4C7
Source: Dhcp-Nap-Enforcement-Client

管理NAP client的工具，napclcfg.msc


Troubleshooting NAP Enforcement
http://technet.microsoft.com/en-us/magazine/2008.04.cableguy.aspx

Troubleshooting NAP Problems
http://technet.microsoft.com/en-us/library/dd348446(WS.10).aspx

Tools for Troubleshooting NAP
http://technet.microsoft.com/en-us/library/dd348461(WS.10).aspx