Here are my comments:

• Since version 7.0 the type field of ir.ui.view is not used anymore. You have to remove it in your view edit_nomfurn
• In action_nomfurn the field nomfurn does not exist. Rename it to view_id or remove the whole line. Also in field res_model rename ig_nomfurn to ig.nomfurn

Try this:

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
    <!-- Top menu item -->
    <menuitem name="IG-OpenERP" id="ig_openerp_main"/>
    <menuitem name="IG-OpenERP" parent="ig_openerp_main" id="ig_openerp"/>

    <!-- Main form -->
    <record model="ir.ui.view" id="edit_nomfurn">
        <field name="name">Nomfurn</field>
        <field name="model">ig.nomfurn</field>
        <field name="arch" type="xml">
            <form string="Nomfurn" version="7.0">
                <field name="cod_f"/>
            </form>
        </field>
    </record>

    <!-- Action -->
    <record id="action_nomfurn" model="ir.actions.act_window">
        <field name="name">View nomfurn</field>
        <field name="type">ir.actions.act_window</field>
        <field name="res_model">ig.nomfurn</field>
        <field name="view_type">form</field>
        <field name="view_mode">view,form</field>
    </record>

    <menuitem name="Nomprod" parent="ig_openerp" id="ig_nomprod" action="action_nomfurn"/>

</data>
</openerp>

I made changes and error still exists

nomfurn_view.xml

<?xml version="1.0" encoding="utf-8"?>

<openerp> <data> <menuitem name="IG-OpenERP" id="ig_openerp_main"/> <menuitem name="IG-OpenERP" parent="ig_openerp_main" id="ig_openerp"/>

    <!-- Main form -->
    <record model="ir.ui.view" id="edit_nomfurn">
    <field name="name">Nomfurn</field>
    <field name="model">ig.nomfurn</field>
    <field name="arch" type="xml">
        <form string="Nomfurn" version="7.0">
            <field name="cod_f"/>
        </form>
    </field>
    </record>

    <!-- Action -->
    <record id="view_id" model="ir.actions.act_window">
        <field name="name">View nomfurn</field>
        <field name="type">ir.actions.act_window</field>
        <field name="res_model">ig.nomfurn</field>
        <field name="view_type">form</field>
        <field name="view_mode">view,form</field>
        <field name="nomfurn" ref="edit_nomfurn"/>
    </record>

    <menuitem name="Nomprod" parent="ig_openerp" id="ig_nomprod" action="action_nomfurn"/>

</data>

</openerp>

 I think your error is in this line
  <field name="nomfurn" ref="edit_nomfurn"/>
Try to chnage this to this one
      <field name="view_id" ref="edit_nomfurn"/> 
Try this :   I hope it will help :D
  <record model="ir.actions.act_window" id="view_id">
       <field name="name">View nomfurn</field>
       <field name="res_model">ig.nomfurn</field>
       <field name="view_type">form</field>
       <field name="view_id" ref="edit_nomfurn"/> 
       <field name="view_mode">tree,form</field> 
    </record>