Problems with GZip filter and IExplorer 8

Hello!

We've got a problem with an old application (servlets 2.3). We have a GZipfilter for some pages (not activate GZip filter in JBoss).
We run the app in IExplorer 8 and when it run an action, Iexplorer give back a file for download.
If we go to the internet options > advanced and we desactivate "Use http 1.1" and "Use http 1.1 through proxy server", it works.

In tomcat, It's the same thing

thanks a lot!