Inconsistent 'invalid-request-cookie' errors

We have recently implemented RECAPTCHA across several web domains due to
bots and spammers flooding our forms. For the most part, it has
drastically reduced our bad form submissions from the bots and spamers.
However, in looking through my ColdFusion logs and error reports, I am
seeing the 'invalid-request-cookie' quite a bit. When I go in and access
the forms and submit them manually, they work fine, but obviously I have
users having issues and this error is being thrown. I have gone into my
settings and added all domains, including third level domains with a shared
key across all domains to try to prevent this but the problem persists.

Any help would be greatly appreciated.

Thanks,
Broc