While trying to make a directory on a system with safe_mode enabled and LANG enviroemnt variable fi_FI@euro I came across the problem that is best demonstrated by the script below:
<?php
$src = '/dir/another/dir2/src';
if( !is_dir($src) ) {
      echo "no dir $src<br>n";
      if( !@mkdir($src, 0755) ) {
          echo "cannot make dir: $src<Br>n";
      }
}
?>
On the 2nd echo $src string is corrupted, the last / is replaced with a special character, which Mozilla displayes as a square.

If mkdir($src, 0755) is replaced with mkdir($src.'', 0755) the memory corruption goes away.