Game segfaults when switching to ConfigMenu several times

[Patrik Schönfeldt]

When I switch to ConfigMenu and back twice or trice the game crashes with bad malloc():

#0 0x00007ffff6fd4027 in ?? () from /lib/libc.so.6
#1 0x00007ffff6fd558e in malloc () from /lib/libc.so.6
#2 0x00007ffff784026d in operator new(unsigned long) () from /usr/lib/libstdc++.so.6
#3 0x0000000000406b22 in Lobby::changeMenu (this=0x645460, menutype=3) at src/lobby/Lobby.cpp:56
#4 0x0000000000409c3f in MainMenu::runItem (this=0x653be0, itemno=2) at src/lobby/gui/MainMenu.cpp:23
#5 0x0000000000407556 in Menu::runSelectedItem (this=0x653be0) at src/shared/gui/menu/Menu.cpp:92
#6 0x00000000004077be in Menu::specificInput (this=0x653be0, parinput=1) at src/shared/gui/menu/Menu.cpp:130
#7 0x0000000000407eda in IE::getInput (this=0x653be0, parinput=1) at src/shared/gui/IE.cpp:38
#8 0x000000000040695c in Lobby::run (this=0x645460) at src/lobby/Lobby.cpp:26
#9 0x0000000000402660 in main (argc=1, argv=0x7fffffffe338) at src/lobby/Lobby-Test.cpp:14)

This happens all the time and is very easy to reproduce, so no further debug output is added here. (If everything works fine exept at my machine, I will hand in a dump later.