Trouble with Slider on theme…

Hi all,

I recently purchased a theme called themebox 1.2 from themeforest. I like the theme but there is one bug that I just can’t seem to figure out. In the backend I have a choice of 5 sliders. The one I need to use is displaying all posts instead of the post I choose. I checked settings and the default it what I want so I am not sure why this is happening.

The author of the site is not returning my enquiries so it looks like I am on my own.

This is the code for the slider:

<div class="main_image">
<img src="<?php bloginfo('template_directory'); ?>/timthumb.php?src=<?php bloginfo('url'); ?>/wp-content/uploads/<?php echo get_post_meta($post->ID, "sliderimg", $single = true); ?>&h=335&w=600&zc=1" alt="<?php the_title(); ?>" />
    <div class="desc">
        <a href="#" class="collapse">show/hide</a>
        <div class="block">
            <h2><a href="<?php the_permalink() ?>"><?php the_title(); ?></a></h2>
            <p><a href="<?php the_permalink() ?>"><?php echo get_post_meta($post->ID, "slidercontent", $single = true); ?></a></p>
        </div>
    </div>
</div>
<?php  $my_query = new WP_Query('category_name='.get_option('tbxl_slidercat').'&showposts=4');
while ($my_query->have_posts()) : $my_query->the_post();
?>
<div class="image_thumb">
    <ul>
        <li>
            <a href="<?php bloginfo('template_directory'); ?>/timthumb.php?src=<?php bloginfo('url'); ?>/wp-content/uploads/<?php echo get_post_meta($post->ID, "sliderimg", $single = true); ?>&h=335&w=600&zc=1" alt="<?php the_title(); ?>"><img src="<?php bloginfo('template_directory'); ?>/timthumb.php?src=<?php bloginfo('url'); ?>/wp-content/uploads/<?php echo get_post_meta($post->ID, "sliderimg", $single = true); ?>&h=38&w=50&zc=1" alt="<?php the_title(); ?>" /></a>
            <div class="block">
                <h2><a href="<?php the_permalink() ?>"><?php the_title(); ?></a></h2>
                <p><a href="<?php the_permalink() ?>"><?php echo get_post_meta($post->ID, "slidercontent", $single = true); ?></a></p>
            </div>
        </li>
    </ul>
</div>
<?php endwhile; ?>
  </div>

Any help on this is totally appreciated..