Im running Windows 7 64bit and had the same problem on my XP 32 so the problem lies within this retarded ethernet adapter from Cisco.
Product: Cisco linksys
This guy has the same problem http://www.justanswer.com/computer-hardware/5sd3h-does-linksys-ae1000-need-unplug-its-usb-port.html
Anyone that might have a trick for this to be fixed would be appreciated. i tried without the extension length cable so direcly plugged into several USB ports in the backside and now frontside of my chassi and still problem persists.
I could randomly get DC and a yellow (!) on the connection even tho its connected.... i tried "allow pc to turn of the device to save power" unchecked and still no success.