[kh99]

Well, I guess if "youtemplate" is an existing vb template or one that's being rendered somewhere else, you'd want just the preRegister, like:

if ($vbulletin->userinfo['userid'])
{
    require_once('./includes/functions_user.php');
    $avatar_url = fetch_avatar_url($vbulletin->userinfo['userid']);

  $avatar = $avatar_url[0];
  $cus_avatar = '<a href="profile.php?do=editavatar"><img src="'.$avatar.'" border="0" alt="" /></a>';

  vB_Template::preRegister('yourtemplate',array('cus_avatar' => $cus_avatar));
}

In any case I don't know why it would interfere with another mod.