Listen Server crashes on creation (never used to?)

so, I start gmod/SP and I want ot mess with my friends, so I want to make a listen server (I’ve done this MANY times before)
When I pick 2/4/8/whatever players and press Start Game, when I get to “Initializing Game Data” or “Sending Client Info” (depending on when I started the server) I get “HL2.EXE has stopped working”, which never really used to happen.
My specs, ofc.

https://dl.dropbox.com/u/19296530/Things/Images%20of%20other%20stuff/facepunch/my%20specs.png

My ports are forwarded etc. etc. so I don’t know what the problem is.

[editline]30th November 2012[/editline]

Oh right I need a crash dump where are those again?

[editline]30th November 2012[/editline]

hl2.exe stopped working bottom text


Problem signature:
  Problem Event Name:	APPCRASH
  Application Name:	hl2.exe
  Application Version:	0.0.0.0
  Application Timestamp:	50aaaa87
  Fault Module Name:	client.dll
  Fault Module Version:	1.0.0.1
  Fault Module Timestamp:	50a676bd
  Exception Code:	c0000005
  Exception Offset:	00366470
  OS Version:	6.1.7600.2.0.0.256.1
  Locale ID:	3081
  Additional Information 1:	0a9e
  Additional Information 2:	0a9e372d3b4ad19135b953a78882e789
  Additional Information 3:	0a9e
  Additional Information 4:	0a9e372d3b4ad19135b953a78882e789