Vista - Trouble in the tower. (Buttons gone, ect...)

I recently formatted and reinstalled Vista myself, (the laptop was delivered
with Vista pre-installed when I bought it). I have reinstalled all programs
and drivers more or less like it was before I formatted now and for about a
day things were running smooth.

Yesterday a few small things is starting to happen though.

On the start menu I no longer have the option to go into hibernation or even
shut down the computer, for this I have to log out first... When I push
Ctrl+Shift+Esc, the task manager doesn't pop up, neither does that option
appear on the menu I get when pushing Ctrl+Alt+Del...

When I log on and off my (administrator) account the screen goes black and
the monitor loses signal for a few seconds before coming back.

I am running a Norwegian version of Vista but before formatting I was still
able to type "cmd" to start the command prompt but now I can only get it
started by typing the Norwegian word for it... (Don't know if this problem is
related to the others).

I know some of this sounds like it has something to do with my graphics
card, but I have tried several different drivers without any change of this
problem, (it's an NVIDIA 8600M GT card).

I have tried to the best of my ability to search through the forums here but
have found nothing similar to help me. If anyone can help me or point me in
the direction of a solution I would be grateful.