In the google code htmlhelp link: http://code.google.com/p/htmlhelp/wiki/CHM
you can see all the viewers and some formats that happen to be in some chm and not others. That is why you can see in perfect condition some and not others.
This is just a seccion of the above link:
Microsoft never released the format specification, but there are a few reverse engineered descriptions of the format:
- Unofficial CHM Specification
- Matthew Russotto's Microsoft's HTML Help format description
There are some tools which allow to read the contents of CHM files:
- libmspack — a library for Microsoft compression formats
- Microsoft HTML Help Viewer
- xCHM — a CHM viewer for UNIX (Linux, BSD, Solaris), written by Razvan Cojocaru
- JouleData Solutions' CHM Viewer — a comercial 100% native Cocoa .chm file viewer for the Mac OS X platform
- GnoCHM — a CHM file viewer. It is designed to integrate nicely with Gnome.
- Chmox — a Mac OS X CHM viewer
- KchmViewer — a Qt/KDE based viewer of CHM files