When the There login gives you the message 'your avatar is already logged in' then a -prior- attempt at logging in failed. This message will only come up on the second or third attempts at logging in, because when you give your name and password, the servers log your avatar in and then wait for the connection from the client. No connection is of course established, and it will time out, but for the immediate moment your avatar is in fact logged in and waiting for the client.
To fix this, the symptoms of why you cannot log in on the prior attempt need to be reproduced.
Please wait a while since your last attempt at logging in, to make sure that your last login attempt has timed out. 10-15 minutes should do.
Then visit this web page in Internet Explorer:
https://webapps.prod.there.com/login/login.xml
It will give you a login prompt, and you can log in, and it will go through all the steps it's doing as you log in. At some point, it may stop, and possibly give an error message. Please send e-mail to help@there.com with the symptoms you see, at which phase the login process stopped, and any error messages exactly as you see them (word for word).
Technical Support will then be able to help with fixing the problem or working around it.