CAR SHUTS OFF WHEN PRESSING CLUTCH.?

I have a 2004 ford focus 5 speed and when you press the clutch as in slowing down the car shuts off. This has only happened twice in about a month period. I thought it might of been the battery since when i checked the sticker it was bout in 08 but I had that tested and its still good. I know it might be a switch but before I spent the money I would like to get some feedback.