The issue is documented in Cisco bug ID CSCsd22910.
When the PIX Cisco IOS Software is upgraded from 18.104.22.168 to 22.214.171.124, users with passwords longer than 11 characters that were saved in the configuration of the PIX can no longer authenticate.
For a workaround, after upgrading the PIX, re-configure the users and their respective passwords.
Alternatively, upgrade the software to one of these versions. Refer to Software Download: Cisco PIX Security Appliance Software:
Firewall - PIX 500 series
PIX version 7.x