I currently have stained, pine, clapboard siding on my house. Mostly on the east side, the boards seem to be curling some, and the nails seem to be backing themselves out of the boards. some, at least an inch.

I am plannning to have vinyl siding installed over this. Obviously, I will need to drive these nails back in before I install the siding, but how concerned should I be that these nails will continue to back out and bulge the vinyl siding after I Install it? Also, the boards that are curling a little, should they be removed and replaced with anything first?

Thanks.