I get a pop up saying that I have logged on to another computer. This is not the case?

This is not a virus or a threat...you are logged into yahoo messenger and when you go to yahoo mail...you will get that message....that is how the software works...you cannot be logged into yahoo e-mail which is a source of chat and the Messenger at the same time...........This is not a virus, nor a threat.....and it cannot be fixed.....that's how the software was designed..............