I know this problem very well: we encountered it when first playing the game, at the time of its release. At the time, that meant contacting Sierra, waiting for them to find a fix and to send a disc with this fix. Now, you can just download a
patch from their site.
A
major problem with it, though: it changes the interpreter, and will therefore make your previous savegames incompatible, and you'll have to restart the game.
It wasn't that fun 12 years ago, I guess it won't be now either. Yet, GK is interesting and well-written; replaying through part of it is not
that bad.
I guess that will teach you to always check for patches
before starting to play a game. Although I must say that Sierra's site is especially unhelpful, and doesn't list half of the patches. My advice is to just browse the
ftp server and download anything that bears a name that may relate to the game you want to play, to check if it may be useful. It usually feels like a waste of time but, as you see, it actually isn't.
(we really need a "cheerful" smiley, as in "don't be too sad", not "I'm happy"; well, that's what the previous one was supposed to mean)