Concercing your login problem:
These are configuration files resp. the user and password database. You can not execute them directly.
You can view them using cat, more or less (a word game ;-) like this:
bash-2.04# cat /etc/passwd
bash-2.04# more /etc/passwd
bash-2.04# less /etc/passwd
(to quit less, press "q")
Alternatively, to filter the lines containing the username you may use grep:
bash-2.04# grep <username> /etc/passwd
If you do so: do you find your username in passwd and shadow? Posting the line from passwd might be helpful, but please don't post any lines of /etc/shadow, this file should be kept private.