Whenever I try joining a game, a window comes up saying "Please Wait. The requested operation is taking longer than expected. Press the ESC key if you would like to cancel"

Then I wait a minute or two, and it says:

"I'm sorry but the account name and password your provided are not valid on this server. Be sure that you correctly typed in your account name and password" or something like that

This happens on EVERY server I try to join, whether or not it has people playing on it. Can someone PLEASE help me figure out how to bypass this? Thanks a LOT!