[CentOS] PAM_shield locking me out?

Yesterday I installed pam_shield and followed the testing suggested and thought all was well. today I find that I cannot get to my email account, I can login via ssh okay (uses keys) but su and sudo give segmentation faults. I am guessing due to the pam module causing a problem. As I cannot do remote login as root and sudo and su use pam I appear to have locked myself out. Any words of wisdom from those a little more knowledgeable? Why do I keep trying new things - I like to improve my system and harden it against constant script kiddies (many different triers per day), but despite reading all the instructions I fall into a hole I cannot climb out of. Hopefully someone has an idea BTW - the console also fails to allow login TIA Rob