We are having intermittent problems from certain machines with true credentials being denied. For example, using a windows 7 machine on our Server 2012 native domain, remote desktop to the domain controller will connect/reconnect all day... then a login later in the day might say the password is incorrect and deny access to the server with ANY correct credentials -- even the administrator account. This problem is isolated to the local PC or terminal server when this happens, and it does not resolve itself over time. Logging out and logging back in to the offending PC will not solve the problem, but in all cases so far, restarting the machine will allow it to connect to servers via RDP with credentials that were previously rejected. I had this problem again today on my Windows Server 2008 terminal server connecting to either domain controller (DC1 and DC2) and several other servers... but some servers connect with no problem. We have one domain, so there are no trust issues. We can ping the servers that we cannot connect to via RDP, and they are available on the network by DNS name and IP.
In the security audits, there are lists of failed login attempts. I believe these are connected to the login issue, but am not positive. I have read that these warnings shouldn't be anything other than that, but they seem to coincide with the failed login attempts. Security Audit Failure Code 4769 0x14