You could try a product like Jim Goulding's Diffraction Be Gone: http://www.diffractionbegone.com/
You could even DIY your own to see if it gets rid of the problem. All you need is some self-adhesive felt from your local hardware store and a pair of scissors :)
You could even DIY your own to see if it gets rid of the problem. All you need is some self-adhesive felt from your local hardware store and a pair of scissors :)