Apache Web Server - Invalid Response

Hi,

I have a SCO Unix Openserver V6 server which is hosting a website with Apache V1.3 as the http server. The web site has an initial login screen which re-directs to another page once the user name and password has been verified.

When connecting to the website and trying to login, it times out with "error code 64: host not available, background: the gateway or proxy server lost connection to the web server" when connecting through an ISA server with HTTP compression enabled, but if HTTP compression is disabled I can get onto the website ok.

Also I have no connection problems when connecting without going through a proxy or ISA server.

I have also tried this on a server with Apache 2.2 installed and with http compression in apache enabled and disabled but it doesn't make any difference.

I understand that this issue may be a configuration issue on the ISA server but I just wanted to find out if anyone has come across this before and if there is an Apache fix or configuration change to resolve the problem rather than all our web customers changing their server settings?