Stuck with black screen on boot (no signal)

[g.ptic]

Recently, the following problem appeared suddenly:

- Start computer
- Ubuntu splash screen appears with dots
- Screen turns black and switches off (no signal)

This happened on every boot. Previously I had removed all but the latest kernel [linux-lts-trusty (3.13.0-48.80~precise1]), but this may be a coincidence because that kernel started without problems before.

I could not even start my computer in recovery mode, as it hung after mounting additional HDDs (may be related or not). In the end I was able to start it in text mode by adding "nomodeset" to the GRUB boot options.

Switching the display manager to gdm then fixed the problem for me.

Note 1: My OS starts from an SSD.

Note 2: My graphics card is recognised as Mobility Radeon HD 5430

Note 3: The same problem also appeared at the same time on Ubuntu 14.04 LTS 64 bit installed on a different SSD on the same computer. However, there the black screen only appears on every *first* boot. The second boot will be fine -> https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1443144

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: lightdm 1.2.3-0ubuntu2.7
ProcVersionSignature: Ubuntu 3.13.0-48.80~precise1-generic 3.13.11-ckt16
Uname: Linux 3.13.0-48-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.8
Architecture: amd64
Date: Tue Apr 7 20:43:44 2015
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130214)
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.