1. Close 3ds Max
2. Browse to the following local user application preferences directory
Windows VISTA / 7
C:\Users\YOUR_USER_NAME\AppData\Local\Autodesk\3dsmax\2009 - 64bit\enu\plugcfg
Windows XP
C:\Documents and Settings\YOUR_USER_NAME\local settings\Autodesk\3dsmax\2009 - 64bit\enu\plugcfg
3. Rename the BIPED.INI configuration file in this direcrtory to OLD_BIPED.INI
4. Restart 3ds Max, new user application preference file for Biped will be created on startup.