firefox .aspxauth cookie not working

I'm working with .net and when i do forms authentication and set the cookie (.aspxauth) domain ".domain.com" it works in all browsers except FireFox (v11).

the cookie is successfully saved and is validated for subdomain.domain.com but for some reason it seems that firefox is not recognizing/finding it when i'm on the top level domain.com

problem also seems to exist in google chrome

how to get around this?

Thanks in advance

Read https://serverfault.com/questions/153409/can-subdomain-example-com-set-a-cookie-that-can-be-read-by-example-com

You'll likely find that in fact most sites are using some combination of Set-Cookie from the older RFC spec with "Host" values, implicitly without a leading dot (as twitter.com does) or setting Domain values (with a leading dot) and redirecting to a server like www.example.com (as google.com does).