Sudden Error Publishing to Facebook

Hi guys..

Sudden problem with my install of Ultimate Facebook book. Same FB app, same WP Settings suddenly will not publish to facebook this morning.. using Version 1.4.2 on WP Multisite 3.2.1

Here is the error its generating in the logs...

OAuthException: Error validating access token: Session does not match current stored session. This may be because the user changed the password since the time the session was created or Facebook has changed the session for security reasons.

I have a WP multisite install. I have not configured anything on a network wide level.. The plugin is not network activated. Have activated it on a site by site basis.

I have reset the app secret.. I have deleted the app from my FB developer acct and re-granted extended permissions. I have set up entirely new FB app and went through the whole process again.. nothing works.. my FB user if a admin of the page, the developer on the app.. and a super admin in the system.

It almost feel like I have done something stupid.. here.. if each subsite has its own app to publish content to their respective pages.. what if anything should I be putting in the Network Admin settings?

What would cause the error above?