I would expect the situation that you are experiencing to occur when the account details are incorrect. Have you tried connecting to the Db in a SQL session, using your credentials, to confirm that they are correct?
Does your account have the correct privileges assigned to it to enable it to use DBConsole?
Failing all that:
Have you tried connecting to the console from the server itself (assuming that at the moment you're attempting to connect from a PC)? What result do you get?
Have you tried stopping & restarting the DBConsole service (assuming you are using Windows 2003, as the hostname suggests)?
90% of users' problems can be resolved by punching them - the other 10% by switching off their PCs.