I have sort the same issue. the game thinks BOTH the left & right mouse button are the right mouse button. Meaning I need to press them both to click on something (ex. logon).
And I am unable to remap the buttons since the game does not recognize the left mouse button at all.
Tried reinstalling the game and then using the default layout in Windows, however it only works in the menus, ingame the mouse start acting all weird again.
All other games are fine and this worked right up to the latest patch (unable to play since).
edit: I have tried other mice (both wireless and an Acer OEM mouse) and same result.