Problem with Saving Combinations

I have a problem with saving the combinations of products. 

I'm using version 1.6.0.5
You already have access to the site www.mavarreda.it/prestashop/, for, Example, if I go to "Optima-Furniture", then I select the product with id = 230 

http://www.mavarreda.it/prestashop/admin0951/index.php?controller=AdminProducts&id_product=230 

Click on "Combinations", I add a cobinazione to this product and do "Save" presents this fatal error: 

Fatal error: Call to undefined method Tools :: clearColorListCache () in C: \ Program Files (x86) \ Apache Software Foundation \ Apache2.2 \ htdocs \ prestashop \ classes \ Product.php on line 1482 

This problem does not allow me to save combinations that I just added. 
It is a very serious problem, since I block the creation and modification of a combination.
I see that is the method clearColorListCache () that is blocking me out of business. 

You can help me urgently? Thanks so much.