nfs: task 865 can't get a request slot. What is this?

["Egor Tur" <worldeb@ukr.net>]

Hi.
I see messages in log's:
client1 kernel: nfs: task 865 can't get a request slot
and sometimes:
client1 kernel: nfs: server carter not responding, still trying
client1 kernel: nfs: server carter OK

I mount nfs disks form "carter" to "client1" with next option:
defaults,rsize=8192,wsize=8192,soft,intr,bg

When I do `df -h' on "client1"  process stop when it tries to show
my nfs disks.
When I try go to in catalogue where I mount nfs disks under 
Midnight Commander - this stop and I can only kill xterm.

When I do `ps ax' I see:
1531 ?           D      0:00 df -h
1571 pts/21   D      0:00 mc
1573 pts/22   S      0:00 bash -rcfile .bashrc

But I can go to nsf catalogue under xterm and I can do `ls -l', this work --- I see
files and I can read and write it and create new catalogues.

What is this?
I also mount nfs disks from "carter" to other machine and I cannot problem with this.

Thanx.