anywho, i noticed you get that irritating :can't connect to custom game, install custom game first" error when ya try to join a server.
Uhm, best way to fix it, is open the properties of the shortcut, and you'll notice the "Start in" field is blank.  thats yer problem.  as i run everythin on my D: drive, my "Start In" field looks exactly like this for NS:
D:\SIERRA\Half-Life

you should make sure yours looks the same..err..scratch that.  make sure your spoints to your HL directory..wherever that is.

Anywho, if anyone cares, thats the fix, and if Flay and everyone else already fixed it..Kudos.

On a second note - KFS, i finally managed to drag my sorry (rotten/smelly) carcass over to the forums.  go me.  Too bad the "Roadkill" forumname is already taken  

[edit]
uhh...afttr looking some more, it seems the fix is known, go that.

Never hurts to be helpful, I was gonna post the same thing.  

When I first played NS, everything worked fine. Then next day, whenever I tried to join an Internet game, it would say something like "You cannot join a server running a custom game." I did what you suggested above, and it did solve the problem for a few hours. Now, whenever I try to join, it says "LAN servers can only be joined by local users (Class C)."

Can you offer some insight?

Quote (Premier @ Nov. 02 2002,15:39)

When I first played NS, everything worked fine. Then next day, whenever I tried to join an Internet game, it would say something like "You cannot join a server running a custom game." I did what you suggested above, and it did solve the problem for a few hours. Now, whenever I try to join, it says "LAN servers can only be joined by local users (Class C)." Can you offer some insight?

It seems sv_lan "1" is set whenever you try to run a server, I've only noticed it when starting a Listen server, so I wouldn't know if it's the same for Dedicated or not.