This has been addressed before:
here
and a couple other places…
When I upgraded to Firefox 3, I had the same problem (as others did).
Even if you haven’t told your browser to display type larger (command +), to see your whole Stats graphs in FF3, go to View>Text Size>Normal ~ or just press command and zero.
If you haven’t already, see http://ww.wp.xz.cn/support/topic/211801?replies=4
It says that in Firefox 3 Preferences, the “Privacy” tab, “Accept third-party cookies.”
Thanks alot! I had just upgraded, and I didn’t know why I should allow cookies from third parties (huh?). But now I know that it allows me to see my blog stats!