Locked screen flashes between vertical bars and terminal screen
 

Ubuntu 9.04 works fine, I have just installed Ubuntu 10.04 Lucid Lynx without problems, it runs fine but after a while the screen starts flashing and the only way out is to reboot with ctrl-alt-del.

First of all I get a pale purple screen with blocks of random colour in the middle then it goes on to flashing between two screens. In one the top half of the screen is vertical black and white stripes and the bottom half is black, in the other it is a terminal screen with this distributed across it:
----
Starting common Unix printing system cupsed
Pulse Audio configured for per-user-sessions
Enabling additional executable binary formats binfmt support
Checking battery state
----
On the latest occasion the text was "could not write bytes: Broken pipe" repeated all over the screen, followed by "checking battery state".

1. have you tried to reboot with Alt+PrintScreen+ sequentially reisub, maintain Alt+PrintScreen down and slowly, leaving like three seconds between each one, hit r e i s u b? I remember this with "Raising Elephants Is So Utterly Boring"? That way, the disks are sync'ed and mounted read-only before reboot, which is safer.
2. Check your screensaver settings ... set it to none. System > Settings > Screensaver

Locked screen flashes
 

thecarpy
I have removed all the screensaver and power management settings as in the past (with Mandriva perhaps?) one of them put the computer into a state I couldn't get it out of.

Locked screen flashes
 

It has been suggested that I should re-install the video driver by pressing F4 when booting from disk, I couldn't find an appropriate option - see attached screen shots when pressing F4 and F6.

What is your graphics card? can you post the contents of /etc/X11/xorg.conf (if you have a file named like that)
What is the output of Do you get any errors in Xorg log file? Xorg log file is located in:
/var/log/Xorg.0.log ... the zero can also be one (1), post both parts where you have an error ... a line with an error starts with (EE).

Flashing screen locks
 

thecarpy
I have tried your recommendation, and alt-prtscr-R then alt-prtscr-E stops it and enables me to open another session.

Answers to your questions:
1) Intel 82845 G/GL Brookdale G/GE.
2) There is no xorg.conf file.
3) Output from lspci is at end of this posting.
4) /var/log/Xorg.0.log - have versions: 0, 0 old, 1, 2, 3, 4 and 4 old. Version 1, 2 and 3 all have what looks like a relevant error, I have attached a file:
(EE) intel(0): No valid modes.
(II) UnloadModule: "intel"
(II) UnloadModule: "ch7017"
(II) Unloading /usr/lib/xorg/modules/drivers/ch7017.so
(II) UnloadModule: "tfp410"
(II) Unloading /usr/lib/xorg/modules/drivers/tfp410.so
(II) UnloadModule: "ivch"
(II) Unloading /usr/lib/xorg/modules/drivers/ivch.so
(II) UnloadModule: "ch7xxx"
(II) Unloading /usr/lib/xorg/modules/drivers/ch7xxx.so
(II) UnloadModule: "sil164"
(II) Unloading /usr/lib/xorg/modules/drivers/sil164.so
(II) UnloadModule: "vgahw"
(II) Unloading /usr/lib/xorg/modules/libvgahw.so
(EE) Screen(s) found, but none have a usable configuration.


chris@chris-desktop:~$ lspci
00:00.0 Host bridge: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE DRAM Controller/Host-Hub Interface (rev 01)
00:02.0 VGA compatible controller: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 01)
00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 01)
00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 01)
00:1d.2 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 (rev 01)
00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller (rev 01)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 81)
00:1f.0 ISA bridge: Intel Corporation 82801DB/DBL (ICH4/ICH4-L) LPC Interface Bridge (rev 01)
00:1f.1 IDE interface: Intel Corporation 82801DB (ICH4) IDE Controller (rev 01)
00:1f.3 SMBus: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) SMBus Controller (rev 01)
02:05.0 Multimedia audio controller: C-Media Electronics Inc CM8738 (rev 10)
02:08.0 Ethernet controller: Intel Corporation 82801DB PRO/100 VE (LOM) Ethernet Controller (rev 81)

I have found out what the problem is in 9.04 - it is nothing to do with the screen. I checked the meaning of an error I was seeing on startup - "Could not load lib/modules/2.6.32-22/generic/modules.dep” and this does not exist on disk, only one directory exists, although when I press [esc] in bootup I can see several options.
I imagine that when I accept the default at startup it can't find the version it wants which causes several problems.
All working on 9.04 now, but I'll forget about 10.04 until I have to!

This is now solved (sort-of) as although I gave up on 10.04, I have installed Ubuntu 10.10 successfully.
There were a couple of file access problems to fix and I had to reselect the display. I've no idea whether they might have caused the 10.04 problem.