No ssh connection with root or other user

[PascalC]

i want to login to my vServer with ssh and putty. When i connect to the server with putty, i am able to enter username and password. when the password is wrong, i get "Access denied." But when it's right putty stops and i get "Server unexpectedly closed network connection".

In the logfile of my server, i get:

sshd[5153]: error: Could not get shadow information for NOUSER

smbd[1845]: [2012/05/26 21:33:23, 0] printing/print_cups.c:cups_connect(69)

smbd[1845]: Unable to connect to CUPS server localhost:631 - Connection refused

smbd[1845]: [2012/05/26 21:33:23, 0] printing/print_cups.c:cups_connect(69)

smbd[1845]: Unable to connect to CUPS server localhost:631 - Connection refused

sshd[5229]: error: Could not get shadow information for NOUSER

I've tried the root account and the ip-adress from the server. And i've tried a ftp user on a subdomain which is allowed to ssh-connect. I always get this error. I've restarted the ssh several times. Also i've tried the SSH-Terminal within Plesk and get the error:"Connection could not be established with host: Failed to read messages".

When i look into /var/log/sw-cp-server/ there is:

ERROR: Installation will not continue
Warning! Not all packages were installed.
Please check if your system services are operable.
Please, contact product technical support.
usermng: neither PSA_PASSWD nor PSA_CRYPTED_PASSWD environment variables are set. unable to determine user's password
filemng: opendir failed: Permission denied

System error 13: Permission denied
usermng: PAM Error: Bad password: too simple
PAM Error End
2012-05-26 23:13:22: (log.c.135) server stopped
2012-05-26 23:15:28: (log.c.75) server started

Any ideas?

Thank you very much!