[xwiki-users] CSRF Error when trying to edit access rights

I am trying to set up access rights for a page that I created, and when I try to revoke view permissions for a particular user, I see the following error: 2015-03-04 01:29:42 - CSRFToken: Secret token verification failed, token: "xykyhIj3uArxuDcDQU9JsA", stored token: "ncSmP4I2YiP6QkKCMAguDw" Why am I seeing this error, and what could I do to fix it? (I see this error repeatedly)