Recently I've noticed that that while flying I will occasionally get error prompts for allegedly missing scenery items, either mentioned by name such as "can't find model inf_large_pier_depot in library" or numerically such as 0x001245 or something similar. The errors don't crash the sim, I just click OK in the error box and they go away but it's annoying to have your flying interrupted. Funny thing is, when I check for the named items in the SCENEDB folders they're there. I am very diligent when installing scenery to make sure everything goes in the right folders. Can anybody explain what causes these errors?