Help:NFS mknod failed

this is existing issue for this nfs client, which mounts windows exported
file system, and this is only one UNIX box has this problem, other boxes are
fine.

Here is from messages file.

Jan 24 03:11:10 venus nfs: [ID 664466 kern.notice] NFS mknod failed for
server arc: error 2 (RPC: Can't decode result)
Jan 24 03:11:11 venus last message repeated 5 times
Jan 24 08:09:43 venus ip: [ID 390400 kern.notice] dst FFFFFFFF src 7F000001

I can't umount it with -f, or fuser -k, it just stuck there after issued
command.

And this only thing to resolve it is to reboot this nfs client, which is
very annoying.

Please help.