From: utzoo!decvax!harpo!npoiv!alice!sjb
Newsgroups: net.games
Title: Re: more Zork questions -- **SPOILER**
Article-I.D.: alice.892
Posted: Wed Sep  1 07:27:51 1982
Received: Sun Sep  5 02:07:50 1982
References: randvax.729

To get past the curtain of light, walk through the curtain, then
walk through one of the walls (north, south, east, or west); I
forget which one.  When you get back, walk through the curtain 
again and you're there!

Now, the answer to the riddle room (her's the big spoiler part):
When in the room, just say:
well
and BANG!  You're in.