I just recently had to install 2009 from map 2008. When I open drawings last worked on and saved in 2008 and open them in civil 3d 2009, I get drawings that freeze up upon opening. Some will eventually open, showing errors. Others will never open and just freeze up. Any suggestions?
2009 is like R13, a big flop! Make sure you install all the service packs.
You might also try opening the older files with Recover. Although I don't recall any specific issues I had when going from 2008->2009.
Start with some of our most frequented solutions or visit the Installation and Licensing Forum to get help installing your software.