A search on Google groups reveals plenty on the green pen. Indeed, a number of threads do indicate that it was a hoax which actually started on the audio newsgroups.

See http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&threadm=43vlj6$43l@access1.digex.net&rnum=3&prev=/groups?q=cd+green+jj%40research.att.com+philips&hl=en&lr=&ie=UTF-8&scoring=d&selm=43vlj6%2443l%40access1.digex.net&rnum=3 (from 1995)

Second post quote: "I think it's time we all recall how "green pen" stuff got started.

It started, with me (among others) watching, when a techie type

net.audio reader said "well, if you're so worried about the

laser light leakage, why don't you paint the outsides of your

CD black to catch it", in a discussion where somebody was offering up an observation that "CD players are dangerous because they have a laser inside them".

A few weeks later, somebody took this sarcastic quote

seriously, and announced that indeed green permanant markers

improved the sound of the audio out of a CD player."