host-iMac:~ host$ idl

dyld: Symbol not found: _inflateReset2

  Referenced from: /System/Library/Frameworks/ImageIO.framework/Versions/A/Resources/libPng.dylib

  Expected in: /Applications/itt/idl71/bin/bin.darwin.x86_64/libz.1.dylib

 in /System/Library/Frameworks/ImageIO.framework/Versions/A/Resources/libPng.dylib

remove libz.1.dylib from /Applications/itt/idl71/bin/bin.darwin.x86_64/

:)