I have a 2003 domain which im in the process of bringing up to 2012 .It currently has a mixture of 2012 and 2003 domain controllers. All FSMO roles have been moved over to 2012 server and im slowly demoting the 2003 servers. Since the work started I have noticed some strange behavior with authentication. When users boot up and logon in the morning some of them cannot logon as they get a message saying the logon or password is incorrect when its not. They reboot then it works. Another user is trying to change their password, but it tells then it doesn't meet the complexity requirements when it does.
Have attached GPO for passwords and logon
Can anyone assist with taking steps to find the cause of these issues?