Check your settings again to make sure auto focus and focus assist are disabled. Also set the AF setting on your lens (or camera body) to manual focus. In manual exposure mode, set your shutter to a relatively high speed (anything above 1/125). It sounds like your camera may be trying to focus before shooting.
Another possible problem may be with your media. The camera may have problems trying to write to the card. If you have another card, substitute it and format it in the camera. If you don't have another card, back up the images then do a low level (full) format on a PC, then format again in the camera. The low level PC format will totally clear the card and will check to see that it's writable. Formatting in the camera will set the proper file system and folder structure.