Server upgrade from 1.7.4 to 1.7.8 and placed blocks have dissapeared

after I upgraded the server I have found that older parts of the world have things that are gone. I had purple stained glass, numerous flowers, horses, and now they are gone. The stained glass was placed in a building. I had extra glass in a chest and it is still there. There are only two of us on the server, so it wasn't a user act. Not sure what you can do - but thought you'd like to know. I can post the world file if you like. Just noticed that the released version says it is 1.7.9, but I am on 1.7.8???