I have been using Ubuntu 12.04 LTS for over a year in my Toshiba "Satellite C850 P5010" laptop. For several months there is sometimes a peculiar behaviour during start-up. Generally there is no problem, and I get the purple welcome screen with password prompt following an audio cue (like a drum-roll). But from time to time I get a black screen with some text on it (some different observed variations are described below) and I can either go on to a login or reboot or sometimes a force quit by continuously pressing the Power on button, which I understand is to be avoided as far as possible.
The Toshiba 850 is supplied without any OS, so I got outside help to install the linux and windows systems. My Ubuntu OS is on a primary partition (50GiB ext3). There is also a Windows7 primary partition (50GiB ntfs) which is seldom used, but seems to be in order. My data files are in secondary partitions (fat32 for the Windows data, and ext3 for the rest, many are still empty, 20 to 30GiB each in the hard disc total of 320GB). Swap partition is 4GiB.
Internet drivers were not readily available, so my advisor introduced an appropriate system file. I have been following the instructions to do a "make" and "make install" with this file every time the kernel was updated, to regain web access. After updating the kernel to Linux 3.2.0-55, the "make" command yielded some error messages at the end, so I was advised to uninstall that update with all dependencies through synaptic, and return to the previous kernel Linux 3.2.0-54. That works fine as far as internet and everything else is concerned, but I do not get any more updates for linux kernel. I have mentioned this just in case it is relevant, as I don't really know what a kernel is or does.
Starting problem variations when logging in to Ubuntu are generally as follows.
(happened a few times, but not recently) Black screen had text " [OK] " at top right corner (without the quotes), and and blinking cursor at left. Mouse (keypad) pointer was present and moving. keystrokes generated random characters on screen. Had to force quit.
(does not happen now, last was in January) Black screen had following text:
" get clip ID fail -1  param:4 rel:0 "
Cursor was present. (?Keystrokes generated random characters? can't remember exactly! probably Alt, Ctl or Escape keys) On entering my password, the purple GUI login screen appeared with audio cue and password prompt. I could continue normally and subsequent startup was also OK. On some occasions Ctl-Alt-Del led to successful restart.
(this has happened very occasionally) Black screen with no text (?) and no response to any keystrokes, having to force quit.
(this happens more often now, and more frequently) Black screen with following text:
" Ubuntu 12.04.4 LTS Toshiba850 tty1 "
" Toshiba850 login: _ "
(entered name to get password prompt):
" Password: _ "
(entered password to get $ prompt):
Typical text content:
" Last login Fri Mar 21 06:56:54 IST 2014 ontty1 "
" Welcome to Ubuntu 12.04.4 LTS (GNU/Linux 3.2.0-54-generic-pae :i686) "
" * Documentation: https://help.ubuntu.com
" 20 packages can be updated "
" 16 updates are security updates "
" thomas@Toshiba850: ~$ _ "
As advised, I switch to root user with ( sudo -i ), and password, followed by ( reboot ), which nearly always results in a successful restart sequence.
I have noted that Ctl-Alt-Del works sometimes to restart from the black screen, but can't remember under which specific conditions. With variation 4, the capslock key LIGHT does not respond, but the key must be active because after one operation the name entry appears in upper case! The numlock key light however comes on and off.
During the booting delay, typically around 10 seconds, the screen may remain either purple or black most of the time, or sometimes a black screen with some text on it flashes momentarily. The starting behaviour is simply not consistent. It is akin to some mechanical instability causing a fall in different directions, or the random throw of a dice.
My advisor was not able to diagnose the problem, and suggested I seek forum help.
My understanding of computers is extremely limited -- no command line knowledge, and my use is mostly limited to text files in a word processor. I even try to avoid using a computer or internet as far as possible. By training I am a mechanical engineer, in my late sixties and admittedly old-fashioned.
If I need to provide any more information, or try any commands, please let me know the exact syntax, and mention any precautions. I have been living with this problem for some months now, and would be grateful for any help in solving it. I have tried to record my observations as faithfully as I can remember things, but it may not be 100% exact. Thanks =TeeSquare=