Validation of Anti-XSRF token failed.

I have a web forms app that works great except for 1 problem. I have a Google login option. I can sign in using a google acct. But when accessing a page that uses a database, and then try to log off, I get this error message ... Validation of Anti-XSRF token failed. I have read several posts about this error and can't seem to find a solution.
Any help is greatly appreciated!
Jeff