External screen does not update in Fedora 20

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I have installed Fedora 20 on my quite new Dell Latitude laptop as dual boot with windows 7. I am usually working on my computer on an external screen which is connected to my computer using a docking station. But when using fedora I get problems with my external screen, problems that I suppose are somehow linked:

1. The external screen does not update. That means e.g. that when switching tab in firefox the window doesn't update and still the content of the old tab is shown. I can make the window update by clicking on the frame of the window thus reactivating it. Another example could be when typing commands in the terminal: what I am writing appears seconds after writing and when scrolling up and down in the terminal window is all a mess. Also, the mouse sometimes leaves a track behind itself. The window on the external screen can also be updated square by square by running the mouse over the window that I wnat to update. That leaves a track of upadated window behind the mouse. This is only an issue on the external screen.

2. I cannot make the external screen the primary screen instead of the build in build-in screen in the laptop. When attempting it simply keeps the build-in screen as the primary.When attempting to turn off the build in screen it wiil jsut give an error and log out.

3. If I attempt to start up with the computer closed, the external screen will just remain unrecogniced and black.

These problems does not display when using Windows.

EDIT: System information:

Dell latitude with i7 processor and 64-bit OS (fedora 20).

Graphics card: nvidia NVS 5200M and an integrated Intel HD graphics 4000 Desktop environment: gnome External monitor is a Dell U2412M.

Drivers: I am not sure how to obtain this information (still new to the world pof linux)

I would be very happy for suggestions for a solution!

Mathias