Not able to boot

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http://forums.fedoraforum.org – Hi, I have a problem with one older computer. It is ASUS K52N. There is debian x64 installed with gnome graphical environment. After installing gimp 2.6 gnome is not able to start(after booting I can just see terminal and after typing startx there is just mouse cursor). I wanted to install another system but it does not boot any cd or dvd anymore. What can be the problem? (HowTos)