In the latest phase of an ongoing battle with computer makers over the allegedly eco-unfriendly nature of materials they use in manufacturing, environmental activist group Greenpeace on Tuesday hit HP’s Palo Alto, Calif., global headquarters. Its members painted the message “Hazardous Products” on the rooftop of HP’s building and sent the company’s employees automated phone calls from actor William Shatner — yes, Captain Kirk and Denny Crane — urging HP to phase out toxic chemicals in its products.