[squid-users] Random authentication popups

I have setup Squid to perform authentication via NTLM and everything
is working fine with the exception of 1 odd error. At random times
throughout the day, and for no apparent reason, an authentication
popup will be presented to the user. Merely clicking "cancel" will
allow the user to view the site.

The proxy server has not yet been deployed throughout the organization
and therefore only has a very minimal load on it at the moment, yet it
does this random authentication thing.

Does anyone have any ideas as to what might be causing this to happen?

-- 
Scott Jarkoff