That is a horrible workflow filled with danger.
IDML is not intended for roundtrip workflows and CS5.5 is unsupported under Yosemite.
You should both be using the same version of InDesign on supported operating systems.
What kind of graphics are you using, specific around page 29? If you use EPS, avoid them they are often causing problems.
One reason could be that Mac only fonts have been used either in InDesign itself or in EPS files with not embedded fonts or EPS files with postscript fonts.