We need to see a debug log. Enable debug logging from System settings, System, Debugging, and restart XBMC then wait a minute or two for all the startup tasks to finish. Close XBMC and if it hangs just kill it. Now run XBMC again, then close it and again if necessary kill it.
Open the debug log by pressing Windows-R and in the Run dialog type:
"%appdata%\xbmc\xbmc.log"
(including the quotes). Click OK and the log should open in Notepad. Copy and paste the log into
http://pastebin.com/ and post the link it gives you here.
Note that the release version of XBMC, v10.1, is about to be replaced by v11.0. I would try the beta 2 of v11.0 from
http://mirrors.xbmc.org/releases/win32/ because that fixed a shutdown problem that we found in v10.1.
JR