Nikon D3100 shutter "problem"?
Are your pictures properly exposed and are they sharp or are your pictures degraded? Is that 1/3-second you describe a delay between the time you push the shutter release and the time the picture is taken or somthing else? Check to make sure you're in the proper shutter release mode (slider switch to right of the mode dial). Also, your self-timer may be turned on. Your camera allows you to set a 2 or 10 second delay from the menus. If it is set to 2 seconds and turned on, it might seem like a 1/3-second delay. If that doesn't help, you camera is covered by Nikon's warranty. Contact Nikon Service at 1-800-NIKON-US (1-800-645-6687) 9AM-8PM EST, Monday to Friday.