Still can't install (debian 4.0 )

[sts_fin]

The day four of my struggle with plesk. It goes quite well untill dpkg errors with libpam-plesk_8.3.0 & psa-courier-imap_3.0.8

I can get sitebuilder running and working but plesk install with the autoinstaller (swsoft_installer_v3.3.0_build080116.12_os_Debian_4 .0_i386) just dies everytime, please help me. I getting really frustrated have bought the 100-domain lisence, this just really sucks.

Please Help...

Unpacking psa-courier-imap (from .../psa-courier-imap_3.0.8-debian4.0.build83071218.18_i386.deb) ...
dpkg: error processing /var/cache/apt/archives/psa-courier-imap_3.0.8-debian4.0.build83071218.18_i386.deb (--unpack):
trying to overwrite `/usr/sbin/userdbpw', which is also in package courier-authlib-userdb
dpkg-deb: subprocess paste killed by signal (Broken pipe)
Selecting previously deselected package psa-qmail.
Unpacking psa-qmail (from .../psa-qmail_1.03-debian4.0.build83071218.18_i386.deb) ...
Checking for the system groups and users necessary for Qmail...
Checking for the group 'qmail'...
Trying to add group 'qmail'... done

Checking for the group 'nofiles'...
Trying to add group 'nofiles'... done

Checking for the user 'alias'...
Trying to add user 'alias'... done

Checking for the user 'qmaild'...
Trying to add user 'qmaild'... done

Checking for the user 'qmaill'...
Trying to add user 'qmaill'... done

Checking for the user 'qmailp'...
Trying to add user 'qmailp'... done

Checking for the user 'qmailq'...
Trying to add user 'qmailq'... done

Checking for the user 'qmailr'...
Trying to add user 'qmailr'... done

Checking for the user 'qmails'...
Trying to add user 'qmails'... done

Checking for the group 'popuser'...
Group 'popuser' already exists

Checking for the user 'popuser'...
User 'popuser' already exists

done
Selecting previously deselected package mailman.
Unpacking mailman (from .../mailman_1%3a2.1.9-7_i386.deb) ...
Selecting previously deselected package psa-courier-imap-add.
Unpacking psa-courier-imap-add (from .../psa-courier-imap-add_8.3.0-debian4.0.build83071218.18_i386.deb) ...
Selecting previously deselected package psa-api.
Unpacking psa-api (from .../psa-api_8.3.0-debian4.0.build83071224.15_i386.deb) ...
Selecting previously deselected package psa.
Unpacking psa (from .../psa_8.3.0-debian4.0.build83071218.18_i386.deb) ...


===> Checking for the necessary system accounts
Checking for the system groups and users necessary for MySQL...
Checking for the group 'mysql'...
Group 'mysql' already exists

Checking for the user 'mysql'...
User 'mysql' already exists

Checking for the system groups and users necessary for admin server...
Checking for the group 'psaadm'...
Group 'psaadm' already exists

Checking for the user 'psaadm'...
User 'psaadm' already exists

Checking for the group 'psaserv'...
Group 'psaserv' already exists

Checking for the group 'psaserv'...
Trying to add supplementary group 'psaserv' for user 'www-data'... already there
Checking for the group 'psaserv'...
Trying to add supplementary group 'psaserv' for user 'psaftp'... already there
Checking for the group 'psaserv'...
Trying to add supplementary group 'psaserv' for user 'psaadm'... already there
Checking for the group 'psacln'...
Group 'psacln' already exists

Checking for the system groups and users necessary for Apache...
Checking for the group 'www-data'...
Group 'www-data' already exists

Checking for the user 'www-data'...
User 'www-data' already exists

Checking that /opt/psa/bin/chrootsh registered as login shell...

Selecting previously deselected package libpam-plesk.
Unpacking libpam-plesk (from .../libpam-plesk_8.3.0-debian4.0.build83071218.18_i386.deb) ...
Errors were encountered while processing:
/var/cache/apt/archives/psa-courier-imap_3.0.8-debian4.0.build83071218.18_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)