We have just updated AutoCAD 2010 to AutoCAD 2013 at my office and I ran into an issue where the first run initialization is hanging at the License check. It is shown as responding properly in Task Manager and when forced closed by Task Manager, the small license window closes, but the larger AutoCAD start-up window remains and has no way of closing. My coworker was able to install his copy with no issues so I don't believe it is the license. I still have use of AutoCAD 2010, but I would greatly appreciate any help so that I can upgrade.
The same thing happened to me recently when I installed the Building Design Suite Standard 2013. I already had Autocad Architecture installed before this. Opened up AutoCad Architecture, got the splash screen running "First run intialisation" and just froze there. I left my machine running overnight hoping that it will initialise when I come back the next day. But it didn't. I noticed there were 2 Autodesk items on my task bar, I clicked one, and there it was - a window prompt asking if I would like to re-associate all .dwg files to AutoCAD. It was just hiding behind the splash screen awaiting response.