If you are logging in for the first time after the upgrade, you will have to reset your password.
To reset your password, click here: http://www.iva.co.uk/forum/ucp.php?mode=sendpassword
If you are facing problems in resetting your password, please contact us here: http://www.iva.co.uk/contact
You really need to talk to your IP and see what they suggest -who are you with?
We can support and advise you, please don't worry too much, there will be a solution.