kojisin

i came across the same problem.

i believe the problem is, this plug doesn’t follow the rule below.
http://codex.wordpress.org/Shortcode_API#Output

following is a rubbish maybe, but works for me.

--- singlecat/singlecat.php.orig        2009-10-06 21:46:00.000000000 +0900
+++ singlecat/singlecat.php     2009-10-07 02:05:26.000000000 +0900
@@ -11,12 +11,14 @@
 //Actions
 add_shortcode('singlecat', 'sc_shortcode');

+
 function sc_shortcode($attr) {

     $level = $attr['view'];
     $cat = $attr['cat'];
     $posts = $attr['posts'];
     $view = 0;
+    $output = "";

     if($level != "public" && $level != "private"):
         $level = "private";
@@ -41,31 +43,31 @@
       $wp_query= null;
       $wp_query = new WP_Query();
       $wp_query->query('category_name='.$catname->name.'&showposts='.$posts.'&paged='.$paged);
-
-      while ($wp_query->have_posts()) : $wp_query->the_post(); ?>
+
+      while ($wp_query->have_posts()) : $wp_query->the_post();
+        $output .= '

         <div class="post">

-          <h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
+          <h2><a href="'.apply_filters('the_permalink', get_permalink()).'">'.get_the_title().'</a></h2>

-          <small><?php the_time('F jS, Y'); ?></small>
+          <small>'.apply_filters('the_time', get_the_time( 'F jS, Y' ), 'F jS, Y').'</small>

           <div class="entry">
-            <?php the_content(); ?>
+            '.str_replace(']]>', ']]>', apply_filters('the_content', get_the_content())).'
           </div>

-          <p class="postmetadata">Posted in <?php the_category(', '); ?></p>
-
-        </div>
+        </div>';

-      <?php endwhile; ?>
+      endwhile;

+      $output .= '
       <div class="navigation">
-        <div class="alignleft"><?php previous_posts_link('&laquo; Previous') ?></div>
-        <div class="alignright"><?php next_posts_link('More &raquo;') ?></div>
-      </div>
+        <div class="alignleft">'._adjacent_post_link('&laquo; Previous', '%title', false, '', true).'</div>
+        <div class="alignright">'._adjacent_post_link('More &raquo;', '%title', false, '', false).'</div>
+      </div>';

-      <?php $wp_query = null; $wp_query = $temp;
+      $wp_query = null; $wp_query = $temp;

     else:

@@ -73,6 +75,37 @@

     endif;

+    return $output;
+}
+
+
+// import from wp-includes/link-template.php
+function _adjacent_post_link($format, $link, $in_same_cat = false, $excluded_categories = '', $previous = true) {
+        if ( $previous && is_attachment() )
+                $post = & get_post($GLOBALS['post']->post_parent);
+        else
+                $post = get_adjacent_post($in_same_cat, $excluded_categories, $previous);
+
+        if ( !$post )
+                return;
+
+        $title = $post->post_title;
+
+        if ( empty($post->post_title) )
+                $title = $previous ? __('Previous Post') : __('Next Post');
+
+        $title = apply_filters('the_title', $title, $post);
+        $date = mysql2date(get_option('date_format'), $post->post_date);
+
+        $string = '<a href="'.get_permalink($post).'">';
+        $link = str_replace('%title', $title, $link);
+        $link = str_replace('%date', $date, $link);
+        $link = $string . $link . '</a>';
+
+        $format = str_replace('%link', $link, $format);
+
+        $adjacent = $previous ? 'previous' : 'next';
+        return apply_filters( "{$adjacent}_post_link", $format, $link );
 }