As much as I enjoy the companions in New Vegas (much better written and more useful, everyone in Fallout 3 except Fawkes felt useless) but yeah, sometimes they just get in the way. Veronica can be a major offender, despite being one of the most fun companions as even when you tell her to stay at ranged she still likes to jump in front of you and get in the crossfire. Boone can also get you into trouble if he suddenly decides that he doesn't like someone looking at you from a hundred yards away. Indoor areas are the biggest issue: there are some buildings and vaults where you just shouldn't take a companion into as they will go crazy since their AI sees through floors and walls, causing them to run off and go on a rampage even when told to stay close to you.