Environmental activists boldly went to the roof of Hewlett Packard’s roof to protest against “excuses” and “backtracking” over use of toxic materials – then let Captain Kirk deliver their message.

William Shatner recorded a message (audio link) for the firm’s staff which was left on the voicemail of all employees. He said HP had gone back on a promise to produce a computer without the use of any toxic chemicals by 2009 and was now two years behind schedule.

The call came after protesters scaled the firm’s global headquarters in Palo Alto, California and wrote the words “Hazardous Products” (a play on HP) so large that Greenpeace said the text covered an area equivalent to two and a half basketball courts. Clearly recognizing the risks of claims of hypocrisy, the protestors say they used non-toxic children’s fingerpaint.

The toxins at the heart of the controversy are PVC plastic and brominated flame retardants. Greenpeace notes that the former creates the carcinogen dioxin when burned while the latter is released during use and contaminates household dust before building up in humans and animals.

HP concedes it has changed its original timetable but maintains that all its new products will be free of toxins by the end of 2011. (Servers and printers may be excepted from this deadline.) The firm said of the protest that “The unconstructive antics at HP’s headquarters today did nothing to advance the goals that all who care about the environment share.”