Firefox no parla English?

As usual, I'm taking Firefox out for a test drive using its PA counterpart. Anyways, for some reason, on its UI, Firefox doesn't display a single recognizable letter.

IMAGE
http://dl.dropbox.com/u/6580270/FirefoxNoEnglish.jpg

Name of file I downloaded
FirefoxPortableTest_4.0_Beta_9_English.paf

- Font work normal on all other applications, including my native installation of Fx v3.6.13.
- Font work normal on all my other portable apps. I have only encounter this behavior with FirefoxPortableTest_4.0_Beta_9_English.paf

What could be wrong?

System Specs
- WINXP HOME SP3
- Default Language: English US | Keyboard: US.
- Patched to allow themes.
-The theme being used is Called "Brushed 3.5" it is a simple look-like MacOS theme. [I mainly use it for its thinness compared to WINXP default theme and is gray-scale color] It is not one of those full package you see or used to see on the net to help you change your whole WIN system look and feel like an Apple system.

- Installation Path: F:\FirefoxPortableTest
Later on I tried a local install of FirefoxPortableTest for troubleshooting purposes.
C:\Documents and Settings\Username\My Documents\FirefoxPortableTest

NOTE: I've been using this theme for at least 3 years, and this is the first time I see such behavior taking place on any of the application I have run on this system.

Troubleshooting

|After following John T. suggestion to change my theme to the default WINXP theme.
-Font is working right again.

http://dl.dropbox.com/u/6580270/FirefoxNoEnglish2.jpg

I think I found whats wrong.

After 3 years of using "Brushed 3.5" I just couldn't accept that the problem I'm having with PortableFirefox is because of the theme itself.

I put my mind into it and I remember that around December 2010 I ran into a "Lucida Grande" font file download. I like the font so I added it to my Font library. Since then, I've been using it as the theme font.

|After changing the font setting for "Brushed 3.5" to "Tahoma"
-Font is working right again

Font info [from r-click/properties]
Lucida Grande
Modified: Friday, May 30, 2003, 5:11:16 PM

This still doesn't make sense. Why would Firefox not recognize Lucida Grande?

I was so much enjoying Lucida Grande Rrrrrrr