Kelvin's workaround in comment #6 did not work for me. The XP connection always opens in a windowed fullscreen mode instead of a fullscreen mode that takes up the whole screen. Even if I do the workaround I mention in #5 (connect to a non-XP computer that does not manifest the problem first, then connect to the XP computer), I get proper fullscreen on that connection but the problem still reappears with the next connection.
Kelvin's workaround in comment #6 did not work for me. The XP connection always opens in a windowed fullscreen mode instead of a fullscreen mode that takes up the whole screen. Even if I do the workaround I mention in #5 (connect to a non-XP computer that does not manifest the problem first, then connect to the XP computer), I get proper fullscreen on that connection but the problem still reappears with the next connection.