PROBLEM: Phrase Error

[GreyBoy]

What do I need to change? Im stumped

Parse error: parse error, unexpected $ in /home/owner05/public_html/includes/mood_change.php on line 33

Here is the code:

<?php
if (isset($_POST['mood']))
{
	$change_mood = $_POST['mood'];
}
if ( isset($HTTP_COOKIE_VARS[$board_config['cookie_name'] . '_sid']) || isset($HTTP_GET_VARS['sid']) )
		{
			$session_id = isset($HTTP_COOKIE_VARS[$board_config['cookie_name'] . '_sid']) ? $HTTP_COOKIE_VARS[$board_config['cookie_name'] . '_sid'] : $HTTP_GET_VARS['sid'];

		if (!preg_match('/^[A-Za-z0-9]*$/', $session_id)) 
		{
			$session_id = '';
		}
		if ( $session_id )
		{
				$user_id = $userdata['$user_id'];

				$sql = "INSERT INTO " . USERS_TABLE . "(  u.user_mood )
						VALUES ('" .  $change_mood .  "') WHERE user_id=" . $user_id;
				if ( !($result = $db->sql_query($sql)) )
				{
					message_die(GENERAL_ERROR, 'Could not obtain newer/older topic information', '', __LINE__, __FILE__, $sql);
				}

				if ( !($row = $db->sql_fetchrow($result)) )
				{
					message_die(GENERAL_MESSAGE, 'UID Not found');
				}

				$user_mood = $row['user_mood'];

	}
?>