I have a little (it's really not big) neat project that I am working on right now and also have downloaded the new RAC2009 from http://revit.downloads.autodesk.com/...09/RAC2009.exe.
Installation works fine and also I opened a windows family I was creating in '08 and it was fine. Then I tried to open my project and it just keeps crashing, even after I've made multiple copies, auditing and moving the file.