Black screen then log.txt error

Hello,

When i play, after 5-10 mins NS2 crash. I have a black screen, then it shows me a fatal error report.
I have the log.txt file (i can't open it, where i can find it in NS2 folder's please ?)

I bought NS2 yesterday (after i tested the free week).

My config :

Graphic card : Geforce GTX 550 Ti
Processor : Intel Core i5-2320 CPU @ 3Ghz
Memory : 3.47 Go
System : Window 7, 32 bit

Solutions i tried :

Unstall / install the game.
Check cach with steam.
Change graphic config ingame.

maybe my probleme : i don't have the folder : C://...appCommon/Natural selection 2/redist
but i have C://...appCommon/Natural selection 2/_Commonredist.

In folder _Commandredist i have directX ( i double click on it, but nothing change, i always crash).

Thanks for your help !