All of a sudden I cannot use yahoo IM. A window pops up saying another user is on my computer, but that's not

Question

also, suddenly my yahoo home page changed. Did you do that?

Answer 1

Sounds like you are using New Yahoo mail which has a built-in messenger and have the Yahoo messenger installed additionally. When Yahoo detects that you’ve already signed into Yahoo Mail, it will disconnect you when you try to sign into messenger or vice versa - hence the message that you are signed in to another computer. To get rid of your problem simply disable chat in your mail (!) account by clicking the smiley and following the prompts. Yahoo remembers your settings until you change them.

http://help.yahoo.com/l/us/yahoo/mail/ya...

About the 2nd part of your question: yes, Yahoo is updating a lot of features and sites.