No subject

https://developer.apple.com/library/mac/documentation/Carbon/Reference/LaunchServicesReference/Reference/reference.html

However, browsing the forums I got the idea to check Console.app and bingo:
    xCHM: Unknown option 'psn_0_2372163'

Here's the log:

[0x0-0x243243].net.sourceforge.xchm.xCHM: Usage: xCHM [-c <num>] [-t]
[-i] [-h] [file]
[0x0-0x243243].net.sourceforge.xchm.xCHM:   -c, --contextid=<num>
context-Id to open in file, requires that a file be specified
[0x0-0x243243].net.sourceforge.xchm.xCHM:   -t, --notopics
don't load the topics tree
[0x0-0x243243].net.sourceforge.xchm.xCHM:   -i, --noindex
don't load the index
[0x0-0x243243].net.sourceforge.xchm.xCHM:   -h, --help
displays this message.
[0x0-0x243243].net.sourceforge.xchm.xCHM: Unknown option 'psn_0_2372163'

I think I can fix this.

Mojca