The forum

When I start League Of legends on PoL it updates and then lets me login I created a new account and tried to login but it keeps on saying "Invalid username/password combination. Please try again."  I tried over and over and made sure I had the password and username right but I tried it all and it didn't work.

Are you in the correct server? If you create an account in the EUW server and then you try to log in the NA server the error is "Invalid username/password combination", so maybe can be this problem ;)