First, please do not post your topic in multiple forums.
The TNR font is the default that IE uses when it has received
either no format instructions, or conflicting format instructions.
Are you using an external style sheet (e.g., MyStyleSheet.css)?
How, exactly, have you "assigned Tahoma font style" to your
numbered lists? All things being equal, numbered lists will usually
take on the font style assigned to the <p> tag or the
<body> tag, if any.
As you can see, this is not a simple issue. Try a quick test:
1. Create two paragraphs (one or more words each).
2. Select the two paragraphs.
3. Click
Numbered List on the RH toolbar.
4. What do you get when you generate your WebHelp?
Good luck,
Leon