
First solution, I found it by configuring somethings in Firefox's Setting. This one will force Firefox 3 to display all web pages according to our chosen font. The following step shows how to do so.

- In the menu bar click Tools (Alt + T) -> Options...
- Select Content Tab. Then in fonts & colors region, select Advanced..
- Finally, uncheck "allow pages to choose their own fonts, instead of my selection above" then OK.
Second solution, I get this one from the internet[1]. It is very easy, just delete the font from the system and Firefox will use default font for that page.

- Go to Windows Control Panel -> Fonts
- Find and Delete "Lucida Grande.ttf" and "Lucida Grande Bold.ttf"

What I don't like about this one is you will not be able to render pages with "Lucida Grande" (oh!, I am quite a perfectionist). It will use default font for instead of "Lucida Grande" in English and Thai.
Final solution, I come up with the solution when I surf internet on Mac OS X with Firefox 3. I noticed that a problem website rendered correctly in Mac. Therefore, "Lucida Grande" font in Mac must differ from Windows. Fortunatly, I had to port fonts from Mac to Windows for my aunt about a month ago and I now know the way how to do that.

- Copy "LucidaGrande.dfont" in /Systems/Library/Fonts (Mac OS X 10.5) to Windows
- Convert dfont to ttf. You can use a program like Crossfont[2] which has 15-days trial period.
- Find and Replace (Copy&Paste) "Lucida Grande.ttf" and "Lucida Grande Bold.ttf" in Control Panel -> Fonts with Mac's Font.
Resources:
[1] - http://www.thaicyberpoint.com/ford/blog/id/520/
[2] - Crossfont