Doors – Is carpet installation easier before or after installation of doors

It makes it easier for the carpet installer because they don't have the baseboards in the way when they're nailing in the tack strips next to the wall.

On the other hand, it makes things a little more difficult to install the baseboard later because the carpet and tack strips are in the way when you're trying to nail the baseboard to the sole plate in the wall. This is much more of an issue if you're nailing by hand than if you're using a brad nailer. (I've done it both ways; use a nailer.) If you're doing a long wall, it can make lining up the pieces of baseboard a little trickier because the tack strip and carpet can get in the way.

On the whole though, I'd follow his advice and use a nailer to install the trim.

What may be happening is the padding under the carpet is not attached to the floor. Since the installer could not hammer staple the padding to the tile (ceramic?) floor it should have been glued with an adhesive made specifically for carpet padding. Glue is applied to the floor so that a continuous bead of glue will contact the edging of the pad. Also, a less likely cause maybe the carpet itself is loose. To check, at the center of the room that is producing the noise, pinch the carpet nap and pull upwards. The amount of carpet that is pulled away from the floor should be minute. If not it will need to be re-stretched and the tackles checked.