Heyyo,
Ah, I know, you're missing the HL1SP maps. You can either: A) Download them off the svencoop site (has less monsters, too easy IMO...
http://www.svencoop.com/ ), or get them from your HL1 cd, or off a HL1 installation. There's some .bat files that can help you with this.
This link can help:
http://www.svencoop.com/game_manual/startup.html