[deeserge]

и вот такой тоже не работает в IE и Opera, только в Mozzila

function  criticality(form)
{
if(form.CATEGORY_ID.value == 34)
{
      form.CRITICALITY_ID.options[2].style.display = '';
      form.CRITICALITY_ID.options[3].style.display = '';
}
else
{
      form.CRITICALITY_ID.options[2].style.display = 'none';
      form.CRITICALITY_ID.options[3].style.display = 'none';
}
}

<tr>
<td class="field-name">Категория:</td>
<td>
<select id="CATEGORY_ID" name="CATEGORY_ID" onchange="criticality(this.form)">
<option value="35">Консультация</option>
<option value="34">Ошибка</option>
<option value="36">Новое требование</option>
</select>
</td>
</tr>
 
<tr>
<td class="field-name">Критичность:</td>
<td>
<select id="CRITICALITY_ID" name="CRITICALITY_ID" onclick="criticality(this.form)">
<option value="4" style="display: block;">Низкая</option>
<option value="5" style="display: block;">Средняя</option>
<option value="6" style="display: block;">Высокая</option>
<option value="26" style="display: block;">Авария</option>
</select>
</td>
</tr>