I'm having a problem with the way the form tabs are displayed in Firefox. It seems that the background image for each tab is not being displayed, so I get white text on a white background.
I took a screen shot of your sample CRM application and posted it at the following URL:
I just installed the very latest version of Firefox (2.0.0.3) on a brand new computer and it's experiencing the same issue. I would suggest that you test it on your end with this version of Firefox and figure out what's causing this problem. Obviously, Firefox support is essential for any web application.
This is happening on Windows XP. I also installed Firefox on a Windows 2003 server and it had the same problem. Please verify that you're using version FF 2.0.0.3. I think the problem only started after I upgraded to that version.