Problem connecting to remote computer from Management Console

Hi

I have a problem where I am unable to connect to some PC's that have the agent installed. It works on some but not others, it asks for the username and password but when I enter the correct password it just pops asking for the username and password again. I have managed to connect to this PC before.

I have added administrator account to the three local policies 'Logon as a batch job, Log on as a service and Log on locally' and restarted the services.