Stripy pics

Difficult to say without seeing a picture, but its most likely a problem with the image sensor, its associated circuitry or the power supply (within the camera)

Its unlikely fixable yourself and as all cameras with a built in flash have potentially lethal voltages inside I cant recommend opening it to have a look.

Some cameras of a certain era were fitted with faulty sony sensors some manufactures offer free repairs of this fault although in many cases the deadline has gone see http://www.adorama.com/catalog.tpl?op=NewsDesk_Internal&article_num=090707-3
Your best bet would be to contact nikon.

Best of luck