i downloaded CS_Source_final_full_071004-dma.exe
and it worked but
first: there are no characters
i choose T or CT then the game starts (i cant choose a character )
second: when i download any new map it doesnt work and i find a message say that map is version 20 but the game expected version 19

......................................................................
any way,I downloaded counter strike source 2010 but i didnt work and this is the problem :
http://www13.0zz0.com/2010/07/28/22/683704366.jpg
i dont know whats wrong but CS_Source_final_full_071004-dma.exe worked on my PC
i have :
ram: 1.0024 G
vga: 128
cpu 3.00
http://www13.0zz0.com/2010/07/28/22/350942938.jpg
please,any one answer my 3 questions

It actually says what the problem is mate

try search for the MSS.DLL file in windows and copy it to your
game directory

- or try this :

http://www.dll-files.com/pop.php?dll=mss32