ciao.
Ho scritto questo codice che mi funziona correttamente solo su IE mentre su firefox mi passa dei valori un po' strani...

questa è la pagina 1
codice:
<form name="form1" method="post" action="inserimento_fatture_2.php">
...
      
  <tr bgcolor="#CCCCCC">
    <td colspan="5"><span class="style2">Nome azienda

	<? //tiro fuori la lista delle anagrafiche esistenti
	$tutto = "SELECT * FROM gestionale_anagrafiche"; 
    $query = mysql_query ($tutto,$db) 
    or die ("Non riesco ad eseguire la richiesta $tutto".mysql_error());
	echo "<select name=\"nome_azienda\">
	     <option>Seleziona</option>"; 
    while ($valori = mysql_fetch_array ($query))
    {
	 $nome = $valori ['nome_azienda'];
	 echo "<option value=\"$nome\">$nome</option>";
	}	
	echo "$nome";
	echo "</select>";
	?>
    </span><span class="style2">
      
    </span></td>
    </tr>
  <tr bgcolor="#CCCCCC">
    <td width="15%" height="45"><span class="style2">Codice IVA 
      
        <select name="cod_iva1">
          <option>Seleziona</option>
		  <option value="1">nessuna</option>
          <option value="1.1">10%</option>
          <option value="1.2">20%</option>
        </select>
</span></td>
    <td width="18%"><span class="style2">Imponibile 
      
        <input name="imponibile_int1" type="text" id="imponibile_int1" size="6">
,    
<input name="imponibile_dec1" type="text" id="imponibile_dec1" value="00" size="2">
    </span></td>
    <td width="18%"><span class="style2">IVA
  
      <input type="text" name="iva" disabled>    
</span></td>
    <td width="19%"><span class="style2">Subtotale
      
        <input type="text" name="tot" disabled>
    </span></td>
    <td></td>
  </tr>
  <tr bgcolor="#CCCCCC">
    <td width="15%" height="45"><span class="style2">Codice IVA 
      
        <select name="cod_iva2">
          <option>Seleziona</option>
		  <option value="1">nessuna</option>
          <option value="1.1">10%</option>
          <option value="1.2">20%</option>
        </select>
</span></td>
    <td width="18%"><span class="style2">Imponibile 
      
        <input name="imponibile_int2" type="text" id="imponibile_int2" size="6">
,    
<input name="imponibile_dec2" type="text" id="imponibile_dec2" value="00" size="2">
    </span></td>
    <td width="18%"><span class="style2">IVA
  
      <input type="text" name="iva" disabled>    
</span></td>
    <td><span class="style2">Subtotale
      
        <input type="text" name="tot" disabled>
    </span></td>
    <td></td>
  </tr>
  <tr bgcolor="#CCCCCC">
    <td width="15%" height="45"><span class="style2">Codice IVA 
      
        <select name="cod_iva3">
          <option>Seleziona</option>
		  <option value="1">nessuna</option>
          <option value="1.1">10%</option>
          <option value="1.2">20%</option>
        </select>
</span></td>
    <td width="18%"><span class="style2">Imponibile 
      
        <input name="imponibile_int3" type="text" id="imponibile_int3" size="6">
,    
<input name="imponibile_dec3" type="text" id="imponibile_dec3" value="00" size="2">
    </span></td>
    <td width="18%"><span class="style2">IVA
  
      <input type="text" name="iva" disabled>    
</span></td>
    <td><span class="style2">Subtotale
      
        <input type="text" name="tot" disabled>
    </span></td>
    <td></td>
  </tr>
  
  <tr bgcolor="#CCCCCC">
    <td colspan="5"><span class="style2">Causale 

        <textarea name="causale" cols="100"></textarea>
    </span></td>
  </tr>
  <tr>
    <td colspan="5"><input type="submit" name="Submit" value="Inserisci"></td>
  </tr>
...
e questa è la 2...

codice:
<?
include ("menu.php");

$imponibile1 = "$imponibile_int1.$imponibile_dec1";
$imponibile2 = "$imponibile_int2.$imponibile_dec2";
$imponibile3 = "$imponibile_int3.$imponibile_dec3";
?>
...
  <tr bgcolor="#CCCCCC">
    <td colspan="4"><span class="style2">Codice fattura

        <select name="cod_fattura">
          <option>Seleziona</option>
          <option value="fattura_acquisto" <? if ($cod_fattura == 'fattura_acquisto') echo "selected"; ?>>Fattura Acquisto</option>
          <option value="fattura_vendita" <? if ($cod_fattura == 'fattura_vendita') echo "selected"; ?>>Fattura Vendita</option>
          <option value="nota_accredito" <? if ($cod_fattura == 'nota_accredito') echo "selected"; ?>>Nota D'accredito</option>
        </select>
    </span></td></tr>
  <tr bgcolor="#CCCCCC">
    <td colspan="5"><span class="style2">Nome azienda
  
	<input type="text" name="nome_azienda" value="<? echo "$nome_azienda"; ?>">
    </span><span class="style2">    </span><span class="style2">    </span></td>
    </tr>
  <tr bgcolor="#CCCCCC">
    <td width="15%" height="45"><span class="style2">Codice IVA 
      
        <select name="cod_iva1">
          <option>Seleziona</option>
		  <option value="1" <? if ($cod_iva1 == '1') echo "selected"; ?>>nessuna</option>
          <option value="1.1" <? if ($cod_iva1 == '1.1') echo "selected"; ?>>10%</option>
          <option value="1.2" <? if ($cod_iva1 == '1.2') echo "selected"; ?>>20%</option>
        </select>
</span></td>
    <td width="18%"><span class="style2">Imponibile 
      
        <input name="imponibile_int" type="text" size="6" value="<? echo "$imponibile_int1"; ?>">
,    
<input name="imponibile_dec" type="text" size="2" value="<? echo "$imponibile_dec1"; ?>">
    </span></td>
    <td width="18%"><span class="style2">IVA
  
      <input name="iva" type="text" value="<? $iva1 = (($imponibile1 * $cod_iva1) - $imponibile1); echo "$iva1"; ?>" disabled>    
</span></td>
    <td width="19%"><span class="style2">Subtotale
      
        <input name="tot" type="text" value="<? $subtot1 = ($imponibile1 + $iva1); echo "$subtot1"; ?>" disabled>
    </span></td>
    <td></td>
  </tr>
  <tr bgcolor="#CCCCCC">
    <td width="15%" height="45"><span class="style2">Codice IVA 
      
        <select name="cod_iva2">
          <option>Seleziona</option>
		  <option value="1" <? if ($cod_iva2 == '1') echo "selected"; ?>>nessuna</option>
          <option value="1.1" <? if ($cod_iva2 == '1.1') echo "selected"; ?>>10%</option>
          <option value="1.2" <? if ($cod_iva2 == '1.2') echo "selected"; ?>>20%</option>
        </select>
</span></td>
    <td width="18%"><span class="style2">Imponibile 
      
        <input name="imponibile_int" type="text" size="6" value="<? echo "$imponibile_int2"; ?>">
,    
<input name="imponibile_dec" type="text" size="2" value="<? echo "$imponibile_dec2"; ?>">
    </span></td>
    <td width="18%"><span class="style2">IVA
  
      <input name="iva" type="text" value="<? $iva2 = (($imponibile2 * $cod_iva2) - $imponibile2); echo "$iva2"; ?>" disabled>    
</span></td>
    <td><span class="style2">Subtotale
      
        <input name="tot" type="text" value="<? $subtot2 = ($imponibile2 + $iva2); echo "$subtot2"; ?>" disabled>
    </span></td>
    <td></td>
  </tr>
  <tr bgcolor="#CCCCCC">
    <td width="15%" height="45"><span class="style2">Codice IVA 
      
        <select name="cod_iva3">
          <option>Seleziona</option>
		  <option value="1" <? if ($cod_iva3 == '1') echo "selected"; ?>>nessuna</option>
          <option value="1.1" <? if ($cod_iva3 == '1.1') echo "selected"; ?>>10%</option>
          <option value="1.2" <? if ($cod_iva3 == '1.2') echo "selected"; ?>>20%</option>
        </select>
</span></td>
    <td width="18%"><span class="style2">Imponibile 
      
        <input name="imponibile_int" type="text" size="6" value="<? echo "$imponibile_int3"; ?>">
,    
<input name="imponibile_dec" type="text" size="2" value="<? echo "$imponibile_dec3"; ?>">
    </span></td>
    <td width="18%"><span class="style2">IVA
  
      <input name="iva" type="text" value="<? $iva3 = (($imponibile3 * $cod_iva3) - $imponibile3); echo "$iva3"; ?>" disabled>    
</span></td>
    <td><span class="style2">Subtotale
      
        <input name="tot" type="text" value="<? $subtot3 = ($imponibile3 + $iva3); echo "$subtot3"; ?>" disabled>
    </span></td>
    <td>TOTALE

      <input name="totale" type="text" id="totale" value="<? $totale = $subtot1 + $subtot2 + $subtot3; echo "$totale"; ?>"></td>
  </tr>
  <tr bgcolor="#CCCCCC">
    <td colspan="5"><span class="style2">Causale 

        <textarea name="causale" cols="100"><? echo "$causale"; ?> </textarea>
    </span></td>
  </tr>
  <tr>
    <td colspan="5"><input type="submit" name="Submit" value="Inserisci"></td>
  </tr>
..
che ne dite?