go into your control panel > power settings and check to see if there are any standby settings set in power options. from what I have found so far this could be an issue if the system comes out of a standby state. Check the following kb from Microsoft:
I have had similar problems with these two repeating errors when I restarted both domain controllers at the same time and only one of them was a global catalog server. For some reason, when more than one domain controller exists, the one that isn’t the global catalog server tries to authenticate itself and can’t. You then start getting these errors in the logs. Try rebooting the server in question and see if the error goes away. I now follow a procedure whereby I reboot the global catalog server–in my case, the Exchange server–first and then reboot the other domain controller. Of course, you could simply make both of the servers function as global catalog servers.