Issue with Precision M4600 and 82579LM Gigabit NIC

The specs are Win7 Pro 64bit with i7-2720QM and 4gb of RAM on a dock. Issue is when logging in (username and pass are correct and it's connecting to corp domain), login time takes a long time. Once on desktop, network defaults to "Network, No Internet Access". If you unplug the network cable and plug back in, it finds correct corp network and all is good. Have uninstalled and re-installed latest official driver from Dell and behavior doesn't change. Issue is affecting over Dell laptops (Precision M4500) in office. Is this a common issue that Dell is working to address? Thanks!