Ubuntu 13.04 on my computer AMD Sempron 2300+, 2GB RAM, ATI Radeon HD4600 is running normaly from Live CD and from pendrive created by Universal USB Installer. When installed system on my pendrive by creating ext4 partition and install grub on device (/dev/sda) and i try to run computer from it after choosing Ubuntu it starts Running system kernel, Reading starting RAM image and few text operation when system tries to run graphical system screen is going to black - monitor is active and there is nothing displyed on it. I have the same problem with running Fedora 18 with kernel 3.8.x but there monitor is going sleep. On the old Acer Travelmate notebook it work normalny but here i don't know what can i do to fix this problem. Could you help me?