I too have a Samsung NP350V5C running Windows 8. Up until a few days ago, all was fine. Now, if I boot up the system, my function keys work as expected for about 15 minutes. Then, it is as if I am constantly holding the FN button down.
So for instance, pressing F5 will no longer refresh the browser screen, instead it will disable the mousepad. And pressing F2 and F3 causes the volume to increase or decrease.
It really is annoying. The only way around it I have found so far is to reboot the PC, and then it is fine for another 15 minutes.
Also, it isn't a browser issue. The PC can have no apps running and the problem will still occur.
I am sorry I don't offer a solution, but at least you now know you are not alone!
I am an owner of a Samsung NP350V5C Laptop.
The problem I have is that since getting the laptop the FN key is always on. Normal key functions like the numpad or the F-keys do not work even if I hold down the FN key to reverse the 'switch'.
I have searched google for an answer and tried to go through the Samsung website technical help but they don't even list my laptop code to go through their internet help system! Great.
Anyway if anyone has an idea to try out it would be a great help as it is a bit of a pain!
As I said above I have tried google and seen people have said press FN+Numlock but this doesn't work.
If anyone has the time to help it would be much appreciated!!!