first off - why would you restart NFS? (that's rhetorical
You say it gives you "Failed to shutdown" - what failed to shutdown? NFS? If NFS is what you're referring to, have you tried stopping nfs rather than restarting? If so, what happens?
When you connect from the windows machine via samba, what username are you using to connect? Does that user have read/write permissions? Can you write files anywhere from the Windows machine to a linux machine via samba? If you can, who owns the files and what are the permissions? How are you handling user/passwords in your samba config?