Gmod's EP2 doesn't work for me! (And I've searched with no good results)

I have searched this in the forums and have found no results. So yea, the EP2 on gmod isn’t working… in the beginning, Alyx has no sound and when she tries to open the train with the gravity gun, she walks over it and goes into “Civilian” position. If you don’t know what i’m talking about as the position, here’s a You tube link http://www.youtube.com/watch?v=lKip9XcdBik

Notice how the scouts are well… motionless like alyx. Another thing… in the original non-gmod ep2 its all fine and dandy. Any help?

Anyway in FAQ thread, it said to post the PC specs so here they are:

Processor (Tell me if it’s outdated): AMD Turion 2 Dual-Core Processor M500
Ram: 4GB DDR2 RAM
Graphics Card (Tell me if it’s outdated): ATI Mobility Radeon 4100 with AMD M860G
Operating System: Win 7

Most campaign games as HL2 has never worked properly and probably never will in GMod.

Then how come i see SOME people doing awesome gmod gameplay in hl2 like that person that made sharpeYe?

[editline]20th May 2011[/editline]

Oh yea my zombie sounds don’t work. Any fix for that?

BUMP

Some people fixed some of the bugging scripts but it can never be perfect. I remember back in 2008-2009 were there was HL2 MP campaign. Most servers had fixed scripts, so that’s probably what you have seen.