I have not used ICQ messenger for quite some time as I have several Netbooks and have been using Aim Messenger. Well today I used one of my other Netbooks that has ICQ Messenger on it. Although I have an ICQ account I sign in with my Aim account, also Aol email account. But today when I tried to log in with my Aim screen name I found I could not do so. I got a message saying "incorrect log in."
So I tried to sign in with my other Aim account and the same thing happened. I could not sign into ICQ with any of my Aim accounts. And I also tried to sign into ICQ web Messenger with my Aim account and it also would not let me do it. And so I looked on the web and I found out that ICQ have changed their system.
Before, about a month ago you COULD sign into ICQ messenger using either your ICQ account email address and password, or your Aim screen name and password. But now you can only sign into ICQ using your ICQ email address and password. So that is the reason I could not sign into ICQ with my Aim account although I found that I could using my ICQ account.