I have a file that I have been working on for quite some time with no problem. I opened it today and suddenly when I try to select a door in a wall it disappears. I can not seem to select any of the door or window tools. I opened a new file and it does not have this problem, and when I paste from the broken file into a new it works fine. I have a lot of layers and time invested and do not want to have to manually transfer all my layers over. HELP