pam_exim installing , server crashed, please help

[Raj Gautam]

I am working with debian 3.1.
I installed exim as a mail server. In order to enable stmp
authentication with (md5 support) /etc/password (ie through pam), I
installed pam_exim following the instructions at
http://www.e-admin.de/pam_exim/ :
* I downloaded latest version of Linux-Pam-modules from
http://kernel.org/pub/linux/libs/pam/
(http://kernel.org/pub/linux/libs/pam/pre/library/Linux-PAM-0.80.tar.gz)
, untarred in /usr/local/ and inside it downloaded pam_exim from
http://www.e-admin.de/pam_exim/pam_exim.tgz
* configured and make all. all the 'so' files where in respectives
modules directory, so I finally did "make install" which i should not
have done. It installed all the pam so's in /lib/security replacing
the old ones.
*  Exim authentication worked fine with pam_exim.so, 
***
But all the system authentication broke including normal login on tty.  
Now the system  is locked. Non other authentication works including ssh 
Please Help.
Any help is appreciated.

PS:I can get in the box by booting in single user mode but cannot revert back.