<indexterm> entries can not be included in the middle of a table.

This confuses the print-backend so that it can't determine what page
the index entry should refer to, and just prints '???' instead of a
page number or range.

Move two entries a few lines up before the <informaltable>.

en_US.ISO8859-1/books/handbook/multimedia/chapter.sgml

@@ -413,6 +413,9 @@ pcm0: &lt;SB16 DSP 4.11&gt; on sbc0</screen>
     <sect3 id="troubleshooting">
       <title>Common Problems</title>
 
+      <indexterm><primary>device nodes</primary></indexterm>
+      <indexterm><primary>I/O port</primary></indexterm>
+
       <informaltable>
         <tgroup cols="2">
   	  <thead>
@@ -421,7 +424,6 @@ pcm0: &lt;SB16 DSP 4.11&gt; on sbc0</screen>
 	      <entry>Solution</entry>
 	    </row>
           </thead>
-          <indexterm><primary>device nodes</primary></indexterm>
 
 	  <tbody>
 	    <row>
@@ -430,7 +432,6 @@ pcm0: &lt;SB16 DSP 4.11&gt; on sbc0</screen>
 	        correctly.  Repeat the steps above.</para></entry>
             </row>
 
-            <indexterm><primary>I/O port</primary></indexterm>
             <row>
               <entry><errorname>sb_dspwr(XX) timed out</errorname></entry>
               <entry><para>The I/O port is not set correctly.</para></entry>