mod-perl+apache showing html code under IE 5.*

[Paulo Henrique Baptista de Oliveira]

        Hi all,
        I made a homepage with mod-perl+apache+libpgperl+postgresl from potato
packages and tested it under Netscape (Linux). When I showed it for a friend
with IE 5.* and he hits the back button it show all the source code instead 
of going back a html page.
        What can be wrong?
        Thanks,         Paulo Henrique