Hi,
today I read in the swiss forum about a virus hitting web sites.
It helps to update to phpBB Version 2.0.11.
Another solution is
open viewtopic.php
found:

Code:
//
// Was a highlight request part of the URI?
//
$highlight_match = $highlight = '';
if (isset($HTTP_GET_VARS['highlight']))
{
   // Split words and phrases
   $words = explode(' ', trim(htmlspecialchars(urldecode($HTTP_GET_VARS['highlight']))));

   for($i = 0; $i < sizeof($words); $i++)
   {


replace this by:

Code:
//
// Was a highlight request part of the URI?
//
$highlight_match = $highlight = '';
if (isset($HTTP_GET_VARS['highlight']))
{
   // Split words and phrases
   $words = explode(' ', trim(htmlspecialchars($HTTP_GET_VARS['highlight'])));

   for($i = 0; $i < sizeof($words); $i++)
   {
I quote because it was posted in German

------------------
Regards
RF