My first experiences with blogging, so a big thank you to all who've contributed to a great tool...
One simple question: often when I paste code (mainly error messages etc) into the editor any asterisks and underscore characters are treated as formatting directives.
Simply escape them with \*, OR disable the serendipity_event_s9ymarkup plugin elements by options, OR remove the plugin completely, OR install the entryproperties plugin and disable markup parsing for this plugin by entry (multiselectfield form). The "_" should not be touched, as far as I remember.
This plugin is a simple and rather old plugin, "~necessary~" for the PLAIN editor forms.
EDIT. Sorry, I have now read you were talking about comments. That is the same. Either you need to tell you users by adding some text to the template files involved, OR you need to disable comments in this plugin configuration options.