What you are seeing in game is a result of your graphics card/ video settings.
Because NWN was made before the widescreen resolution that happened a few years ago, NWN does not like to be stretched. There are a few things you can try, but there is nothing out there that will change the size of the chat windows/gui.
You can try changing the resolution of the game. Sometimes this can revert NWN back to normal. You can set your video card to No Scaling. This has worked for me before on Nvidia cards. You can also set NWN to run on it's own video display, if adjusting the settings helps.
One other thing you can try, is to roll your video drivers back- however at this point you would probably have to roll it so far back that anything new wouldn't work. If you don't know what you are doing, this option has the greatest potential for screwing everything up.
good luck!