Problem downloading large static content files using forms auth

[thehercman]

I am using forms authentication to protect all content as described in the
kb article below.

http://support.microsoft.com/default.aspx?scid=kb;en-us;893662

This works fine except for files that are larger than about 40 or 50mb at
which point the user gets a 404 error and the httperr log indicates
connection_dropped status.

This is a w2k3 server with SP1 and all security patches installed.

Has anyone seen this before? I have been reading various posts online but
none seem to fit this symptom. Also have tried tuning various meta-base
properties to no avail.

Thanks