I think it would have to be a really, really old Nikon lens if it was a compatability problem. When I was shooting Nikon digital I would routinely use old manual focus lenses with it. But I wasn't using a D100. So that's definately something to check.
If you're using any autofocus 50mm that should not be a problem. I'd check your battery. It's not uncommon to get a bad battery, even a fairly new one, that won't take a full charge. These can give you camera errors. I've had this happen with Nikon and Canon cameras.
I have one battery for my Canon 20D that works fine topside but everytime I take it UW, fully charged no less, I get an error message on my camera and it quits working. This is why I label all my batteries. Makes it easy to remember if one is quirky, needs replaced, charged, etc.
Good luck