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When I try to install any recent version of Ubuntu, the screen shows some green and purple mess (like analog TVs when thers no signal). Then, a black screen. I guess it keeps booting in live/install mode. But I can't see it. I tried installing from CD and USB, I tryed changing some BIOS settings... I installed older versions, like 8.04, and it worked, but after updating the system, it crashes again. That's why I discovered that upgrading Nvidia drivers, made system show a black screen again. After that, I unplugged the Nvidia card and installed 12.04 with onboard card. It worked perfectly. Then, I plugged Nvidia again and system booted, but only showing that black screen again. I keep working with onboard card, so far... The nVidia is a GeForce 8500GT.

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Welcome to AskUbuntu! You seem to not be the only one with issues with this graphics card after upgrading, could you check other questions such as this one and see if any help? – Oyibo Oct 29 '12 at 10:38

Try to boot a live CD or from an USB and press F6 on the first loading screen of the CD/USB. Choose 'nomodeset' with your arrow key and try to install the system again.

Otherwise hold the shift-key when booting the installed system and try to edit the Grub entry by selecting "Ubuntu" and pressing e.

If you don't know how to do this use the wiki or let me know.

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OK, computer boots with nomodeset. Live mode works in 1024x768. Installation works. When PC reboots, it shows: purple screen, no signal input message, then desktop wallpaper without login input or unity interface. Changing to tty1, it shows a message: "[time] [drm] nouveau 00:04:00.0: PGRAPH TLB flush idle timeout fail: 0x001e0101 0x00000000 0x0000002d 0x00148000" and "[time] [drm] nouveau 00:04:00.0: Failed to idle channel 2" or channel 3. And that's all... – jopasso1 Nov 14 '12 at 19:30

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