Camera will only sometimes power up

I have an interesting problem with my spare D1X- sometimes, the camera will power up with no problems, other times, the camera will only turn if it is smacked at the bottom of the body, near the battery contacts, and others it will not power up at all. This seems to have nothing to do with bad battery packs, as the packs all hold a charge and work fine in my other body. Has anyone else experienced this? I'm guessing it may have something to do with the battery contacts? (They appear to be clean.)