I saw an episode of a series many years ago. It might have been 'twilight zone' or there was another series 'the red door'(or something in that line)

There was a person (who I think through a necklace found) could stop time whenever he wanted to. At the end of the episode he had to stop time as there was a bomb heading for them. As soon as he stopped time the bomb was still hanging in the air and a few meters from earth. He could not start time again as it would mean that the bomb would impact and destroy everything.

I know this as vague but I have wanted to see this episode for so long

A Little Peace and Quiet (http://en.wikipedia.org/wiki/A_Little_Peace_and_Quiet)

Thanks QUINN F - Just looked at the episode on the net.

You're welcome.