CHM help files don't display properly until opening in another program?!

November 27, 2014

I am not sure if this is the appropriate place for this.

I downloaded each of the Unigine .CHM files in the downloads section but initially was unable to fully open them. The topic hierarchy on the left displayed correctly, but the "body" on the right remained blank, no matter what topic I selected on the left. I tested loading another .CHM file I found in my Windows directory, and it displayed without error. I re-opened the Unigine CHM again, but it still would not fully display.

I am not very familiar with the CHM file format and decided to try opening the file in a text editor (Notepad++) by right-clicking and choosing "open with..." in the context menu. The CHM is compressed and not directly human-readable, so I closed the text editor. I then again right-clicked the file and opened with Microsoft Help Viewer Executable (can't remember the exact name), and suddenly the help doc was fully viewable, displaying with no errors! The problem somehow fixed itself after opening the file in another program which I acknowledge makes very little sense. :)

A colleague had the same problem and was able to remedy it with very similar steps. We are both running Windows 8. This seems most likely to be a Microsoft problem, but it might also be related to the way the Unigine CHM files were compiled. I post this here in case it helps someone else with the same strange problem.

November 27, 2014

Try right click on downloaded *.chm file, select "properties". As the file has been downloaded from the internet there should be some button on the bottom of the first properties tab for enabling file access without Windows warning and user confirmation. Afterwards the chm file should open and display without problems. This works at least for Windows 7.