=== modified file stock/product.py
--- stock/product.py	2012-01-31 13:36:57 +0000
+++ stock/product.py	2012-03-19 16:37:59 +0000
@@ -221,14 +221,18 @@
         if context.get('compute_child',True):
             child_location_ids = location_obj.search(cr, uid, [('location_id', 'child_of', location_ids)])
             location_ids = child_location_ids or location_ids
-        
-        # this will be a dictionary of the UoM resources we need for conversion purposes, by UoM id
-        uoms_o = {}
+            
+        uom_ids = []
         # this will be a dictionary of the product UoM by product id
         product2uom = {}
-        for product in self.browse(cr, uid, ids, context=context):
-            product2uom[product.id] = product.uom_id.id
-            uoms_o[product.uom_id.id] = product.uom_id
+        for product in self.read(cr, uid, ids, ['uom_id'], context=context):
+            product2uom[product['id']] = product['uom_id'][0]
+            if not product['uom_id'][0] in uom_ids : uom_ids.append(product['uom_id'][0])
+        
+        # this will be a dictionary of the UoM resources we need for conversion purposes, by UoM id
+        uoms_o = {}  
+        for uom in self.pool.get('product.uom').browse(cr, uid, uom_ids, context=context):
+            uoms_o[uom.id] = uom
 
         results = []
         results2 = []