[mod_python] IOError: Write failed, client closed connection.

What is the cause of this error?  I am seeing a bunch of these in my 
application logs when the handler is doing a the req.write to write out 
the page.

Here is the full traceback:

        File "/home/orderform/www/cgi-bin/slither/Driver.py", line 182, 
in process
         self.render( output )
        File "/home/orderform/www/cgi-bin/slither/Driver.py", line 233, 
in render
         self.req.write(ss[1])
     IOError: Write failed, client closed connection.

I read in google searches that this usually happens when the user closes 
their browser before the request is written out.  That is fine but if I 
see so many is there something else that could be going wrong?

Hozi