It's working now!
I typed something in google about msn explorer because I can't use it too so I typed "can't sign in to msn explorer" then clicked many links.. and I bumped into a site where it says "windows update fails" (because I can't check my windows update too..) so I follow the instructions in this site:
http://www.updatexp.com/0x800B0004.html
then... my problem was fixed! Yay I'm so happy.. I don't know the reason why I can't check Hotmail/Yahoo emails, can't sign in to MSN Explorer, can't visit secure site, can't check windows update.. but when I did the instructions on the above website.. It is working now..
Thanks anyway for all your help