It's just parsing the query string incorrectly, using the year instead of the forum. If you're having trouble like eva, change this:
Code:
$forumID=$urlArray[3];
$year=$urlArray[4];
$month=$urlArray[5];
$week=$urlArray[6];
$threadID=$urlArray[7];
to this
Code:
$a=0;
while($urlArray[$a] != "archive") {
$a++;
}
$forumID=$urlArray[($a+1)];
$year=$urlArray[($a+2)];
$month=$urlArray[($a+3)];
$week=$urlArray[($a+4)];
$threadID=$urlArray[($a+5)];