I am playing FO:NV Ultimate. My graphics card is an AMD Radeon HD 6800.

In the game, certain decals will disappear when I approach them and some items are invisible but may still be interacted with. There are two locations in which this behavior has prominently appeared.

• Sunset Sarsparilla Headquarters, upper story

I saw the decals in the upper story meeting room accessible by climbing the fallen section of ceiling disappear as I approached them. Once I was all the way up, they vanished along with the one empty bottle that was visible from that spot. Once on the second story, I found that all objects on the floor (debris, decals, the toolbox, the plunger in one of the bathrooms) were invisible. When I lifted and dropped the bottles with "Z", they turned visible and stayed that way until I looked away from them. Items placed above the floor did not disappear, eg. a coffee pot placed on a desk remained visible.

• Vault 19

In one of the larger rooms, a block of C4 under a couch disappears when I approach it, as does a decal of books and trash next to a bed.

How do I fix this?