Hi sirurich, This sounds like a known issue reported here: https://bugzilla.mozilla.org/show_bug.cgi?id=713014 There was a workaround posted, but I've not tested it myself. Here are the steps. # Go into Yahoo Messenger Options - Change the Window in the dropdown to Tab and press OK. # Then go back and switch it to small window and press OK. The bug has been fixed already by the developers, you could try running a Nightly or Aurora build to use the fix early. Hopefully this helps!