This update fixes sound issues during the cinematics and/or the dialogs.
This is not a game issue but a display and sound drivers compatibility on Windows with Bink video and Miles audio librairies.
The 1.05 update is compatible with current savegames.
You can also start a new game by creating a new player profile without any problem.
Update 1.05 is for the versions on DVD and digital (downloaded version from the online shop).