when i try to enter, a username and password in a web browser for web mail i keep getting "username and password incorrect" or similar. Yet when i log on using a different computer it works fine, there must some setting somewhere but i dont know what it is.
Does it fill in the username and password for you? This is normaly what happens and it has stored the wrong password on your system. If you retype it in it should then remember the new one or go in via another way like the mailbox login box on the portal top right