Gmod Crashing

I just downloaded gmod to my laptop, though I can play SP with no problem, I cannot play MP to save my life. When I join a server, the game begins to lag, then eventually crashes after a minute of lagging in-game, returning the HL2.exe error.
System Specs follow:

Operating System: Windows Vista™ Home Premium (6.0, Build 6001) Service Pack 1 (6001.vistasp1_gdr.100218-0019)
Language: English (Regional Setting: English)
System Manufacturer: Sony Corporation
System Model: VGN-NR430E
BIOS: Ver 1.00PARTTBL
Processor: Intel® Pentium® Dual CPU T2390 @ 1.86GHz (2 CPUs), ~1.9GHz
Memory: 2038MB RAM

EDIT: I’ve tried lowering the DirectX level to 8.1 already, and lowered the graphics to as low as it will go, and i am very stressed right now.

[editline]12:55AM[/editline]

I hope and pray there is a solution to this problem.
G’nite

Wait, now I have a new problem. When booting up gmod, right before the blue progress bar appears, the screen goes black and i get the “HL2 Has Stopped Working”
Damn, I have bad luck.

It’s a gmod problem for the majority of users. Wait for a fix.

coughNot a Bumpcough
can someone PLEASE HELP ME? (or rather)
Would you kindly help me?

Download speccy and post the stuff on screen.

Change your OP to xp with service pack 3 cuz i dont thinks gmod can run on vista