Wow Yahoo! was release they new service, and amazing this service not supported when run on Internet Explorer 7 beta 2 (as I know), when I try to post question, sub menu on category dissappear. look my screen shoot.
update
Then I ask Yahoo! Answer and my question was answerwred by Yahoo! Answer team 
IE 7 Beta 2, as beta software, is not yet bug-free. It fails to display certain aspects of Answers properly. The current production version of IE (IE 6, Windows XP Service Pack 2) does render Answers properly, as do Mozilla Firefox 1.5 and other browsers. By the way, Solidus, the Windows XP operating system doesn’t play a role in this problem.
You can check their answer here
#1
rifie
February 6th, 2006 at 2:56 pmAh, nevermind…
Nanti IE yang akan datang akan tambah keren kok dibanding FF..
*Ngarep*
#2
vnuzday
February 6th, 2006 at 3:59 pmKalau aku sih tetap pake maxthon aja.
#3
aRdho
February 6th, 2006 at 8:28 pmyahoo mail beta juga gag jalan di IE 7.. so?
#4
geblek
February 7th, 2006 at 3:17 pmmasih belom pngen mencoba
#5
vnuzday
February 7th, 2006 at 3:35 pm#ardho: IE sucks????
#6
yonky
February 9th, 2006 at 5:39 amyah untuk sementara ini aku masih cinta ama Firefox dan Opera.
#7
kusaeni
February 11th, 2006 at 10:51 ammaniak Yahooo!!!!!
Y! answer pertanyaanya pakai bhs eng yah?
coba - coba deh ane