To solve the error that .chm file can’t be shown correctly,
1. run notepad.exe
2. copy the following code, and paste
REGEDIT4
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp]
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
"MaxAllowedZone"=dword:00000003
3. save the file with type .reg, such as chm.reg
4. double click the .reg to input it
5. run .chm, it’s normal now.
IT1999: Want convert .chm to html? There is a free software named “CHM Decode” which is only 504KB, single .exe file. The following content is copied from http://gridinsoft.com/chm.php
CHM Decoder may decompile your CHM file (Compiled Windows HTML Help) or e-book and extract all source files. This tool free for use and work easily and quickly.
Step 1 – Press ‘Open’ and select CHM file

Step 2 – Press ‘Go!’ for decompile

Want you convert CHM to HTML and view that in your PocketPC or in your web pages? Try CHM Decoder now!
The program supports command line. Using batch mode, you can convert several documents simultaneously:
chmdecoder.exe [-menu] chm_file [destination_path]