I found that this version has to upgrade and save the AEC objects (created by verticals) to 2010 thus rendering them un-editable and sometimes untouchable as in the case of snapping to them. The rest of my office is still on 2008 ADT and I upgraded to 2010 and I used 2010 to open and grab some stuff from a drawing thus screwing perfectly good ceiling grids.
Note that "just opening a drawing and grabbing some stuff" does not render the file useless to previous versions. It is the act of SAVING said file to the new format that screws up the older versions.
