Login/Register stopped working with cryptic error....

Fatal error: Call to a member function getOne() on a non-object in /var/www/vhosts/oncologyeducation.com/httpdocs/core/cache/includes/elements/modplugin/10.include.cache.php on line 9

$profile = $user->getOne('Profile');

[2011-08-24 13:21:32] (ERROR @ /index.php) modUserProfile: Attempt to set NOT NULL field internalKey to NULL

<?php
	$uid = $_POST['id'];
	$user = $modx->getObject('modUser',$uid);
	$profile = $user->getOne('profile');
	$isBlocked = $profile->get('blocked');
	$message = '';
	$mailChunk = '';
	$email = $profile->get('email');
        $fullname = $profile->get('fullname');
	$mailFrom = $modx->getObject('modSystemSetting', 'registration_reply_email');
	$replyTo = $modx->getObject('modSystemSetting', 'emailNoReply');
	$mailFromName = 'domain.com Registration';



	// unblock message 
	if (($isBlocked == 1) && ($_POST['blocked'] == 0)){
		$mailChunk = 'userUnBlocked';
		$subject = 'You have been unblocked';
	}
	
	// block message
	if ($isBlocked == 0 && ($_POST['blocked'] == 1)){
		$mailChunk = 'UserBlocked';
		$subject = 'You have been blocked';
	}

	
	
	if ($mailChunk != ''){

		$modx->setPlaceholder('fullname',$profile->get('email'));
		$modx->setPlaceholder('email',$profile->get('fullname'));
		$placeHolders = array('fullname' => $fullname, 'email' => $email);
		$message .= $modx->parseChunk($mailChunk, $placeHolders, '[[+', '+]]');
				
		$modx->getService('mail', 'mail.modPHPMailer');
		$modx->mail->set(modMail::MAIL_BODY,$message);
		$modx->mail->set(modMail::MAIL_FROM,$mailFrom);
		$modx->mail->set(modMail::MAIL_FROM_NAME,$mailFromName);
		$modx->mail->set(modMail::MAIL_SENDER,$mailFrom);
		$modx->mail->set(modMail::MAIL_SUBJECT,$subject);
		$modx->mail->address('to',$email);
		$modx->mail->address('reply-to',$replyTo);
		$modx->mail->setHTML(true);
		
		if (!$modx->mail->send()) {
		    $modx->log(modX::LOG_LEVEL_ERROR,'An error occurred while trying to send the email: '.$err);
		}
		
		$modx->mail->reset();
	
	}