To verify, I reinstalled my game:
. uninstalled it
. cleaning the whole pc with CCleaner
. erase all the remaining folder
. clean again with CCleaner
. use installer 1.0: entered key code
. use patch 1.01c
. launch the game: re-renter key code
and there was no problem.
However the installed patch tells the game is 1.01, not 1.01c,
but the patch did installed good.
I use the box version of the game bought from Ageod store, not Steam.
I don't think the installers are different, it should be a Steam problem. So ask Gabbe.