anonymousIdentification to go away when browser closes

Question

I am trying to use aspx anonymousIdentification, but I ran into a problem.

How can I make the cookie go away, disappear, die, when the browser is closed?

I know I can manually, with some code, get rid of it (user clicks on log off, or on a browser close event), but that is not suficient.

Any help would be appreciated. This is the tag in the web.config file:

<anonymousIdentification enabled="true" cookieName=".Blahblah" cookieTimeout="99999" cookiePath="/" cookieRequireSSL="false" cookieSlidingExpiration="true" cookieProtection="All" cookieless="UseCookies" domain=".domain.com" />

Thank you!