What is going on with Yahoo mail?

I try to access it, sometimes it works, sometimes it doesn't. I click on something to get rid of it as spam, it works, or it doesn't. It lags, I get frustrated. I have to go out and go back in again and maybe it works. What is the problem?
Update: I won't upgrad to IE 8, since everytime I upgrade, it gets worse. Can't Yahoo get anything right?
12 answers