Sorry, hast recht. 
Das Problem war bisher, dass die Error Details von NX überhaupt nicht angezeigt wurden. Mit der jetztigen Variante (Schritt 2 habe ich übersprungen, da Putty reibungslos mit root/pwd läuft) werden sie angzeigt:
Code
NX> 203 NXSSH running with pid: 4532
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: IP on port: 22
NX> 211 The authenticity of host 'HOSTNAME (IP)' can't be established.
RSA key fingerprint is 6f:6f:1f:29:b0:6b:25:93:5f:b4:14:82:9d:a3:c4:fb.
Are you sure you want to continue connecting (yes/no)?
Warning: Permanently added 'HOSTNAME' (RSA) to the list of known hosts.
NX> 212 Warning: the RSA host key for 'HOSTNAME'
differs from the key for the IP address 'IP'
Offending key for IP in /cygdrive/c/Users/globus/.ssh/known_hosts:1
Are you sure you want to continue connecting (yes/no)?
NX> 202 Authenticating user: nx
NX> 208 Using auth method: publickey
HELLO NXSERVER - Version
NX> 105 /usr/bin/nxserver: line 18: which: command not found
/usr/bin/nxserver: line 18: .: filename argument required
.: usage: . filename [arguments]
/usr/bin/nxserver: line 652: [: : integer expression expected
/usr/bin/nxserver: line 50: [: : integer expression expected
/usr/bin/nxserver: line 50: [: : integer expression expected
/usr/bin/nxserver: line 50: [: : integer expression expected
/usr/bin/nxserver: line 50: [: : integer expression expected
NX> 280 Exiting on signal: 15]