I have the same problem. I'm using a Dell Optiplex 960 with Windows 7 32 bit and an Intel 82567LM 3 network adapter. I've tried all the drivers available and the problem still exists. The computer worked fine for about one week and then it wouldn't connect to the LAN. In device manager I would get a code 10 (device cannot start) for the intel 82567. The only way to connect is to do one of two things: either shutdown and disconnect the plug from the electrical supply, then plug back in after a few seconds and turn the computer on or I can also uninstall the driver and then reinstall it. I can't do this every day forever and I haven't found any other solution, so I bought an USB ethernet adapter and gave up on the Intel adapter.