I think it unlikely that the cameras firmware has been corrupted but it is possible.
The solution, if the firmware is corrupt, is pretty easy. Download the latest firmware update from the Nikon USA site and preform the update. Even if your firmware is up-to-date it will let you perform the operation and the firmware in the camera will be overwritten by the firmware that you download from Nikon. This is kind of like reloading the operating system on your computer.
I had an odd focus issue with a D300s and this procedure worked for me.