I am trying, so far in vain, to connect to nxserver from tha nomachine nx client.
I checked the most obvious first, nxserver is running, user is added, ssh is running, correct key in che client config...
All seems to be going well then the client throws an error: Server configuration error. Cannot log in. Contact your administrator...which is me.
This is the output from the client:

NX> 203 NXSSH running with pid: 9245
NX> 285 Enabling check on switch command
NX> 285 Enabling skip of SSH config files
NX> 285 Setting the preferred NX options
NX> 200 Connected to address: 127.0.0.1 on port: 22
NX> 202 Authenticating user: nx
NX> 208 Using auth method: publickey
HELLO NXSERVER - Version 3.4.0-8 - LFE
NX> 105 Hello NXCLIENT - Version 3.4.0
NX> 134 Accepted protocol: 3.4.0
NX> 105 Set shell_mode: shell
NX> 105 Set auth_mode: password
NX> 105 Login
NX> 101 User: rob
NX> 102 Password: *********
NX> 103 Welcome to: rob-ubuntu user: rob
NX> 105 Listsession --user="rob" --status="suspended\054running" --geometry="1280x1024x24+render" --type="unix-gnome"
NX> 127 Available sessions:

Display Type Session ID Options Depth Screen Status Session Name
------- ---------------- -------------------------------- -------- ----- -------------- ----------- ------------------------------

NX> 148 Server capacity: not reached for user: rob
NX> 105 Start session with: --link="lan" --backingstore="1" --encryption="1" --cache="16M" --images="64M" --shmem="1" --shpix="1" --strict="0" --composite="1" --media="0" --session="roblocal" --type="unix-gnome" --geometry="1280x974" --client="linux" --keyboard="pc105\057us" --screeninfo="1280x974x24+render"
NX> 595 ERROR: A fatal error occurred in NX Server.
NX> 595 ERROR: The exception id is: D814DA87. To get detailed information about
NX> 595 ERROR: the error search for the string D814DA87 in the system log
NX> 595 ERROR: file (usually '/var/log/messages').
NX> 500 ERROR: Last operation failed.
NX> 280 Exiting on signal: 15

and the first few lines of /var/log/messsages:

Oct 20 11:02:28 rob-ubuntu NXSERVER-3.4.0-8[9264]: ERROR: (exception id D814DA87) NX> 596 ERROR: NXNODE Ver. 3.4.0-6 (Error id eBF9EE9)
Oct 20 11:02:28 rob-ubuntu NXSERVER-3.4.0-8[9264]: ERROR: (exception id D814DA87) NX> 596 ERROR: create session: run commands
Oct 20 11:02:28 rob-ubuntu NXSERVER-3.4.0-8[9264]: ERROR: (exception id D814DA87) NX> 596 ERROR: execution of last command failed
Oct 20 11:02:28 rob-ubuntu NXSERVER-3.4.0-8[9264]: ERROR: (exception id D814DA87) NX> 596 last command: /bin/mkdir -p /home/rob/.nx/C-rob-ubuntu-1008-706382623813267C181BB68588FAC3B3
Oct 20 11:02:28 rob-ubuntu NXSERVER-3.4.0-8[9264]: ERROR: (exception id D814DA87) NX> 596 exit value: 1
Oct 20 11:02:28 rob-ubuntu NXSERVER-3.4.0-8[9264]: ERROR: (exception id D814DA87) NX> 596 stdout:

Any help would be greatly appreciated :-)

Distro: Ubuntu 9.04
nxserver Version 3.4.0-8 - LFE

After mush searching of the forums I finally found a solution to my problem.

The server needs to access the ~/.nx directory in the users home but it lacks privileges.

To fix the problem you need to:

sudo chown username:username /home/rob/.nx

Works a treat now. Also, you have to make sure the key on the client side is the same as the server.

cat /usr/NX/share/keys/default.id_dsa.key

then copy and paste the output to a file (forgot how to use pipes...) and transfer the key to the client.