When logging on to talktalk (tiscali or lineone.net) email accounts, it is impossible to get in to the inbox, the message just comes up that we have 'undefined' new emails in our inbox. This does not happen on our other pc which has not updated to Firefox 5, and the Talktalk helpline have indicated that there is an incompatibility with Firefox 5. I can't work out how to get back to the previous version of Firefox.