Nikon N80

I recently purchase the Nikon N80 SLR and have experienced it 'locking up' on me a couple of times. I can press the shutter release and the lens may or may not focus but other wise it will not take the picture. I solved this problem once by use the reset option but have been unable to correct it a second time. I'm attempting to take pictures outside. There is no error message on the LCD. Any ideas will be appreciated..