Maybe one of the pix is configured with a "Pager x" command. The default for pager commands is 24 lines and this can be changed. If you have one of the pix configured for "pager 0", then you will see only the end when you do a "show run". If you have pix version earlier than 7.0, then this command is in enable mode. For versions higher than 7.0, the command is in config mode.
Please refer the below URL for details.
http://www.cisco.com/en/US/docs/security/asa/asa71/command/reference/p_711.html
Let me know if it helps.
Regards,
Arul
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