Dark Side of the Moon.....speech interaction.

Hi.
my problem is with an older game "Dark Side of the Moon.

Ive installed it via the cd...uninstalled it, and tried the dvd....both installed ok...or so I thought.

Everything works,except the green icon...bottom right..that allows conversation.

It's there when I install the game, but as soon as I click on it,it vanishes.!
Also non of the other points to access the recorded messages or my human form work.
Is there a patch or something to correct this.any help would be most appreciated.
My comp is xp proff..ver.2002...AMD Athlon(tm) xp 2400..2.00GHz...256 mb ram.................thanks...Kosmo