Desktop freeze on NFS share failure

Why does the desktop freeze whenever an NFS share fails? I have set all NFS mounts to soft,intr and yet, if I forget to unmount a share before taking down the NFS server, my desktop freezes. Luckily I have Yakauke running, so I can at least get to a console. But of course the NFS mount cannot be umounted if it doesn't respond. Also I assumed the setting shares to intr, soft would prevent other software from hanging if the share stops responding. Is that not so? Or is there another setting I am not aware of? Any ideas how to prevent this from happening? Emmett