Centos – PAM unable to dlopen(/lib64/security/pam_fprintd.so) causing CentOS/Redhat server to crash

CentOS 6, Parallels PLESK 10.4, Apache

One of my servers went down over the weekend much to my dismay. On the day and time it occurred, my log errors/messages end with this –

/var/log/secure:

Jul 29 03:53:15 u######## su: PAM adding faulty module: 
  /lib64/security/pam_fprintd.so
Jul 29 03:53:15 u######## su: pam_unix(su-l:session): 
  session opened for user popuser by (uid=0)
Jul 29 03:53:16 u######## su: pam_unix(su-l:session): 
  session closed for user popuser
Jul 29 03:53:16 u######## su: PAM unable to dlopen(/lib64/security/pam_fprintd.so):
 /lib64/security/pam_fprintd.so: cannot open shared object file: No such file or
 directory
Jul 29 03:53:16 u######## su: PAM adding faulty module: 
 /lib64/security/pam_fprintd.so
Jul 29 03:53:16 u######## su: pam_unix(su-l:session):
 session opened for user popuser by (uid=0)
Jul 29 03:53:18 u######## su: pam_unix(su-l:session): 
 session closed for user popuser

then immediately afterwards,

/var/log/messages:

Jul 29 03:53:21 u######## kernel: imklog 4.6.2, log source = /proc/kmsg started.
Jul 29 03:53:21 u######## rsyslogd: [origin software="rsyslogd" swVersion="4.6.2"
 x-pid="1370" x-info="http://www.rsyslog.com"] (re)start

/var/log/messages (of that day):

Jul 29 03:53:21 u######## rsyslogd: [origin software="rsyslogd" swVersion="4.6.2"
 x-pid="1370" x-info="http://www.rsyslog.com"] rsyslogd was HUPed,type 'restart'.
Jul 29 03:53:21 u######## kernel: Kernel logging (proc) stopped.

And from /var/log/cron

Jul 29 03:53:20 u######## run-parts(/etc/cron.daily)[29257]: starting awstats
Jul 29 03:53:20 u######## run-parts(/etc/cron.daily)[32242]: finished awstats
Jul 29 03:53:20 u######## run-parts(/etc/cron.daily)[29257]: starting logrotate

That's the last message I get before the server goes down. Everything I've Googled leads me to believe that the session opened for user popuser is a fairly common log entry and shouldn't be considered a threat, but for some reason I interpret that as something not so nice.

Others have mentioned that PAM adding a faulty module could be a bug? I don't even know what PAM is….

Any insight on how to interpret these would be greatly appreciated. I've checked

/var/log/secure
/var/log/messages
/var/log/cron

Are there any other places I could look into to help diagnose this?

Many thanks, SF.