SPS 2003 latest service patch applied.

Integrated windows authentication. both IE 6 and 7.

We began seeing this error a few weeks back, and now see this error with
increasing frequency. Hit the F5 key and the page loads. This error
can occur the first time a user visits the site or on their second or
more visits on the same authenticated session. We are wondering if the
authentication session is timing out and looking to re-authenticate.

Any idea where to start looking?
--
>G< ©