Reverse proxy/IIS keep alive issue (Apache Users)

This error occurs intermittently in our .NET application. It seems the be down the keep alives on IIS and Apache on playing nicely with each other. When the keep alives are disabled in IIS and in Apache they go away 99% but still reappear intermittently. Do any of you have any other suggestions?

---Error in Internet Explorer
Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /arm/Admin/AdminDlg.aspx.
Reason: Error reading from remote server

---Debug in apache error.log

[Thu Jul 19 11:53:33 2007] [debug] proxy_util.c(1378): [client 172.25.80.63] proxy: http: found worker http://crocodile/arm for http://crocodile/arm/Admin/AdminDlg.aspx?dlgDepth=1

[Thu Jul 19 11:53:33 2007] [debug] mod_proxy.c(756): Running scheme http handler (attempt 0)
[Thu Jul 19 11:53:33 2007] [debug] mod_proxy_http.c(1662): proxy: HTTP: serving URL http://crocodile/arm/Admin/AdminDlg.aspx?dlgDepth=1

[Thu Jul 19 11:53:33 2007] [debug] proxy_util.c(1798): proxy: HTTP: has acquired connection for (crocodile)
[Thu Jul 19 11:53:33 2007] [debug] proxy_util.c(1858): proxy: connecting http://crocodile/arm/Admin/AdminDlg.aspx?dlgDepth=1 to crocodile:80

[Thu Jul 19 11:53:33 2007] [debug] proxy_util.c(1951): proxy: connected /arm/Admin/AdminDlg.aspx?dlgDepth=1 to crocodile:80

[Thu Jul 19 11:53:33 2007] [debug] proxy_util.c(2141): proxy: HTTP: connection complete to 172.25.80.63:80 (crocodile)
[Thu Jul 19 11:53:33 2007] [info] [client 172.25.80.63] (OS 10054)An existing connection was forcibly closed by the remote host. : core_output_filter: writing data to the network

[Thu Jul 19 11:53:33 2007] [error] [client 172.25.80.63] proxy: error reading status line from remote server crocodile
[Thu Jul 19 11:53:33 2007] [error] [client 172.25.80.63] proxy: Error reading from remote server returned by /arm/Admin/AdminDlg.aspx

[Thu Jul 19 11:53:33 2007] [debug] proxy_util.c(1816): proxy: HTTP: has released connection for (crocodile)

Thanks
Ian

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