You are getting a specific error about your username or password. So there is the issue. While your username and password may be right, they may not be right for the remote computer. Computer's don't just deside to let a valid account not work. Either your info is wrong (caps lock on, num lock is not on, etc..) or the remote PC user or rights have changed.
Check the remote PC accounts again. Is this a computer on the domain? Is the right domain selected? Local PC account, domain accunt being used?