Why is Yahoo Mail displaying incorrectly in Firefox?

[bdk3clash]

When I open Yahoo Mail in Firefox, it looks like this:
http://i139.exs.cx/img139/4738/yahoomai7wr.jpg

In Internet Explorer it's displaying normally. This just started happening in Firefox today after weeks of functioning just fine.

Any ideas?

[Peca277]

I don't know... but my Yahoo Mail all day (for the past few days) keeps showing that I have the same number of new messages as the first time I logged in... even when I have 0 new... or more.

Example, login 9am 1 new message inbox, 2 bulk and those are actually there. Noon, it shows I have 1 new message inbox and 2 in bulk, but really I have 0 inbox and 4 bulk. I sometimes have to send myself an email for the new messages to show up! Can anyone explain why this is happening?!