Where did "Untitled Font Set" come from?

["Chuck Martin" <cm -at- writeforyou -dot- com>]

Between Tuesday night and Wednesday morning, the display of topics in
RoboHTML 2000 got
messed up (for lack of a better technical term). When I view a topic
from within RH (even thoug I do the actual authoring outside, I still
sometimes view within), the fundamental paragraph style definitions
are gone, replaced with "Untitled Font Set". When I look iin the
Paragraph Styles drop-down list, there are 3 new entries:
Untitled Font Set 1
Untitled Font Set 2
Untitled Font Set 3

In the Edit Style Sheet dialog box, all the styles I've defined show
as using one of these. The Font Set dialog box show these 3 listed
among the others there. The style sheet itself remains unchanged. Two
lines are added to the headers of files in True Code view that I don't
think I've seen before:

<!-- $MVD$:fontset("Untitled Font Set 3","sans-serif") -->
<!-- $MVD$:fontset("Untitled Font Set 2","Courier
New","Courier","mono") -->

What happened? I am suspecting that my project file got corrupted
somehow. I did a search in eHelp's knoledgebase and in this group and
came up with no hits on "Untitled Font Set."

Fortunately, the generated WebHelp is not affected (although those 2
HEAD lines remain, adding to the file weight). At this point, it's an
annoyance, but one I want to identify the cause of and fix. Plus, if
it is a problem with the project file, I am concerned that other
problems may cause issues that are more than mere annoyances.

Chuck Martin