Inspiron 17-5748 Windows 8.1 FIFA 15 Keyboard not working

Hi I just bought the Dell Inspiron 17-5748 (Windows 8.1 - 64-Bit, Intel Core i7-4510U 2.00GHz, 8 GB RAM, NVIDIA GeForce 840M, 2 GB DDR3).

Before buying I asked a service staff whether the system requierements of EA FIFA 15 will be achieved by the Dell Inspiron 17-5748. And he confirmed they would be. Actually it seemed to be working. The game starts normally. Graphic looks very good, but...

unfortunately the keyboard is not working at all neither the mouse (you just see the cursor but it´s impossible to select sth by click). So the problem is I can´t pass the start up screen and I am likewise not able to play the game.

I already tried connecting an external keyboard, mouse and gamepad but the result was the same. I also rolled the driver versions of keyboard and mouse back and even tried to uninstall them completley but nothing changed. A update of the bios-version was also effectless.

I searched in the internet to solve the problem and found several posts on the issue http://en.community.dell.com/support-forums/software-os/f/4677/t/19600469, http://answers.microsoft.com/en-us/windows/forum/windows8_1-gaming/i-cant-get-past-the-start-up-screen-of-the-game/74297ba0-3097-4fd4-b606-56d285e1f1aa).

so I am not the only one beeing confronted to this problem...but I can´t find any solution.

Playing the game on the notebook was one of the main reasons to buy it...so please help me to solve the problem!!!

Kind regards