Greetings.
I don't known the reason, but today I tried to use that classic combination of keys to enter text mode and no way. The last time I tried was about a week ago and worked perfectly.
Now, however:
F1: Graphical (KDE)
F2 ~ F11: The screen stays black without the login text
F12: Black screen with green squares all around (like huge radioactive pixels)
Additional Info:
OS: Mageia 2
Desktop: KDE
Graphic Card: nVidia 7950GT (proprietary driver 304.84)
If more info is needed, let me know.