Sorry to hear about this. I believe I know the answer to this question: http://support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?idx=415294&modelname=UN55ES7150F&modelcode=UN55ES7150FXZ
Purchased a new Samsung Series 7 7150 Led TV yesterday. The Facbook App does not work keeps giving me that my username is not recognized. My user name is correct that I am using and the correct password. I have regisitered and linked the accounts...called support and even they cannot get it to work. Samsung supprt told me that it is a Facebook App Problem and they will notifity them of the issue. I do see where this has been a problem for many others after searching the internet. Can someone please help!!