Hello, yesterday i received a key-gift from a friend of dota 2, so i opened the gift > downloaded Dota 2 (There was also an option like "downloading Dota 2 test" but my friends told me it wasn't important for the game running so i didn't download it) after downloading i clicked on "Play" and try running the game but it appeared an error "Failed to load the launcher DLL" so i tried the option "verify integrity of game cache" but didn't work, then i deleted the folder "Bin" in steamapps > common > dota 2 beta and tried again to restart the pc/steam but didn't work. Any solution to this error?

Specs:
> Microsoft XP version 2002 Service Pack 3
> AMD Athlon(tm) XP 2800+
> 2.09 GHz. 1.00 GB RAM

I apologize for possible bad grammar, because english is not my native language. And thank you for your time.

-edit-
I forgot to say, before deleting the folder BIN, my error was "FAILED TO LOAD THE LAUNCHER DLL: NULL"