You can try to change the Driver settings in the Console Tools for the NIC your using.

Go to Console and enter CTRL + ALT + T then select Modify Driver and choose the NIC that you want to modify.

I did research on the net and found this link below concerning the "NETDEV WATCHDOG" messages w/ the a specific Intel chipset but don't know what you have. I have supplied a link for your research and testing.

http://www.intel.com/support/network/sb/cs-009209.htm

Also Googling the power option that I mentioned previously can prevent those errors did you test after making the changes to the power settings?