I'm sorry to hear that you're having an issue with these Apps.
Two things to try:
1. Go into the Apps Manager (Settings) and delete the Apps. Then, reinstall those specific Apps fro the list of available Apps and see if that helps.
2. The other option is to check the login/password section under Manage Apps, also in the Setup Menu.
I purchased the Samsung LCD Series 6 650 .... especially because of the @internet tools. I have successfully connected to my wireless network and used the apps..youtube, facebook, etc. However, neither the Facebook or the Pandora application seem to work. When I click on the application, I simply see a icon with the white dots circling, and the word "connecting." I have let this go for over an hour.
I have seen similar issues with Netflix, but none with the connecting screen. Any suggestions. this is a brand new tv, and this was the feature, that ultimately made my decision. I definately don't want to return it.