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I upgraded my system from 11.10 to 12.04. After pressing the Power On button, I don't get the Ubuntu boot screen with the dots. All I get to see is a full black screen until the login screen is displayed. I have a Lenovo T420. I have also enabled the LUKS encryption and currently, I type the LUKS passphrase on a full black screen which is accepted and the system continues to boot. Is this a known issue on ubuntu 12.04 ? Is there a known fix for this issue ?

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I had the same problem when I installed.But soon I realized that this was caused due to graphics driver.After then I installed the required graphics driver and things came back to track.

Try one of them by setting in your grub.cfg I am not sure which one was the right one.

linux   /boot/vmlinuz-3.0.0-12-generic root=UUID=3e9185555-317f-4587-9b3c-d6b77262a598 ro recovery **nomodeset**

linux /boot/vmlinuz- root=/dev/disk/by-id/ata-TOSHIBA_MK6465GSX_FHGJKHKH-part3 **splash=silent quiet showopts vga=0x317**

Only try those which are inside two asterisks ,and dont copy whole line, otherwise result could be weird.

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I hardly remember what I did ,but perhaps kept vesa as default and then later I installed Intel HD driver.Please dont convict me as its now totally out of my mind. – perilbrain Aug 5 '12 at 17:18
There was another related question where they pointed to as the solution. I tried it, but that didn't work as well. I was left with a Gnome 3 classic only ubuntu with a much lower resolution. I had to rollback the changes. – Lakshmikanth Aug 5 '12 at 18:00
I have made some changes you can try one of them...Not sure about there 100% success. – perilbrain Aug 5 '12 at 18:14
I tried adding nomodeset to /etc/default/grub and so, now it looks like GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset". This one shows the plymouth during boot, but always boots me into gnome 3 classic only with a max resolution of 1024x768. I guess I am getting into the recovery mode by default. As for the second option, I am not able to see it in the grub.cfg at all. I am still stuck. – Lakshmikanth Aug 6 '12 at 2:58

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