Hi,
I found a solution for this problem. It’s a known bug from wordpress because of 64bit systems. Here’s the fix:
Open “bb-includes/gettext.php” and change the following code passage to:
// $MAGIC1 = (int)0x950412de; //bug in PHP 5
$MAGIC1 = (int) - 1794895138;
// $MAGIC2 = (int)0xde120495; //bug
$MAGIC2 = (int) - 569244523;
$this->STREAM = $Reader;
$magic = $this->readint();
if ($magic == ($MAGIC1 & 0xffffffff)) {
$this->BYTEORDER = 0;
} elseif ($magic == $MAGIC2) {
$this->BYTEORDER = 1;
} else {
$this->error = 1; // not MO file
return false;
}
Source: http://forum.wordpress-deutschland.org/sprachdatei/24-wordpress-deutscher-sprache-5.html (German)
Then it should work!
Greets,
jetson
Hehe, hi fel64. 
Thanks for your reply!
I just put an underscore at the end of the folder name and it worked.
Yes, there wasn’t any change before concerning my language problem. I tried to switch to the spanish language file but it doesn’t get recognized by bbpress, too. No change.
