InvalidAuthenticityToken on login (sometimes)

Hi!

I have a Rails site in production and every once in a while a user can’t
login because of an invalid authenticity token, most of the time it
works fine though.

Could this be something to do with character encoding? Maybe it fails
because some character is included in the token that isn’t encoded
correctly?

I started a new thread because all other problems with the tokens seem
to be reproducable reliably.

Regards,

Stefan