How should I diagnose ERROR 1045 during MySQL installation?

I recently setup a MySQL server and encounted the following error when I ran the mysql console (and incidentally the administrator GUI tool):

ERROR 1045: Access denied for user: 'root@localhost' (Using password: YES)

I had done a standard installation and reached the last page in the configuration wizard when the security check stage failed with an error suggesting that the MySQL port was blocked by a firewall.

closed the wizard, checked there was no firewall running and then and tried running mysql and the administrator GUI and found the same error in both cases.

Can anyone suggest a solution to the problem or perhaps resources for diagnosing MySQL problems.

You may need to reset your root password. I had a similar problem a while back.

Details: How to reset the root password

The basic process involves stopping the server and restarting it with a special initialization script.