Can you right-click GoToMeeting's orange flower icon in your system tray (the area next to your clock) and see if there is a log-out option available in that menu? If not, can you choose Preferences from that same location and see if the checkbox under Sign in is marked?
I believe I know what is happening; that sounds like your task bar, which has bigger icons that what your system tray should have. Check the corner where your clock is, and if you don't see an orange flower there right away, click the arrow and more icons should appear there.
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