Toshiba P-50 Laptop Ubuntu Mate 14.10 Beta2 Intel/Nvidia Gt740M graphics 12Gb RAM Intel 7260 NIC

Laptop experiences spontaneous screen freezes or reboots.
These occur and have occured with several flavors of Ubuntu, both LTS and Beta.
Screen freeze looks like many horizontal lines arranged in semi-transparent 'columns' across the screen* and is accompanied by loss of keyboard, touchpad, or mouse input.
Only option is manual powerfail.

Reboots are like any manual powerfail and just before they occur appear as the screen freeze pic but only for a brief instant.

I have so far been unable to locate any obvious error or anomaly in /var/log files at the time of occurence.

Any troubleshooting help would be appreciated.

*Note: I'm too new here to be allowed to post attachments but have a pic of screen freeze for examination.

Given your hardware configuration with an nvidia graphics card on a higher end laptop, I assume that your laptop is designed to use nvidia's optimus technology:

http://en.wikipedia.org/wiki/Nvidia_Optimus

Can you confirm this is the case?

I also assume your are dual booting. If so, is windows functioning properly?

The symptoms you describe may be due to overheating. If that is the case, the lockups would tend to occur after the laptop had been on for a while and you would here the exhaust fan running full blast. If you are experiencing lockups on both windows and linux, you may have accumulated a lot of dust and lint on the exhaust vents. If it's a linux only thing, you are probably experiencing issues with optimus which is not natively supported under linux. There are hacks around to get it to sort of work but I'm not familiar with them. With optimus not supported by your operating system, you may be running solely on the nvidia graphics card instead of switching back and forth between the integrated intel graphics and the nvidia graphics card which may lead to overheating as well. Also, I've seen problems reported with some nividia graphics cards and recent ubuntu and distros based on ubuntu but those are usually problems with the installation freezing. It might be worth trying fedora or pclinuxos and see if you get better results.

Yes, the Nvidia X server settings allows for choosing either the Nividia card or the Intel. I have tried using the Noveau drivers, the Nvidia 331, 340, and 343 drivers from xorg-edgers with the Nvidia card.
I have switched off the Nividia card and used the integrated Intel card.
If it's overheating I have never observed a temp higher than 53C on this system during any system activity.
I don't run games of any kind.
The fan has never run at higher speeds for more than a brief period during OS install.

It's not an overheating issue. Rather it appears to be a problem with your hybrid graphics. Initially, there was no support from nvidia for its optimus technology. However, the linux community hacked together a solution called "bumblebee" which worked around nvidia's lack of support. Later, nvidia came out with optimus support in its linux driver which it referred to as "nvidia-prime". For an explanation of the two systems see:

http://swapniel99.wordpress.com/2014...-nvidia-prime/

So much for the history. Unfortunately, that was not the end of problems with optimus. If you google "ubuntu optimus nvidia" you will see many reported problems with nvidia optimus and recent ubuntu releases starting with 13.10. Here's some methods people have tried to work around this problem:

http://askubuntu.com/questions/41245...a-prime-gt650m

I would suggest giving some of those a try. The one I'd try first is probably this one:

Hi,

Welcome to LQ!

I would run some diagnostics on the Laptop. Look at;You should run memtest86+ which is on the above linked LiveCD;You should run the memory diagnostics at least a few passes of the test to insure a valid test, that is unless an obvious error is shown. Most times you can clean the edge connector for the memory stick to solve connector issues. sometimes just removing and reinserting will get you a positive valid connection.

WARNING: Be sure to have all power disconnected and use good grounding techniques when handling the memory. You can use a commercial wrist strap or use a 10MΩ resistor between yourself & a wired ground lead to insure grounding. You can place the resistor on a watch band then connect the ground wire to the opposite end of the resistor.

Cleaning of the stick edge connector can be done with 20# typing paper cut in one inch wide strips folded and alcohol by wiping in one direction with a new wipe with each cleaning.
Hope this helps.

A hardware issue with the ram would give problems in both windows and linux. Unless that's true, I wouldn't bother with memtest, especially with all the reported problems with optimus and later ubuntu releases.

Hi,

I see no mention of a Windows problem in the OP. I would still run memtest86+ to rule out any potential issues. It only takes a bit or two to cause failure/lock.

Unless you have a crystal ball that is showing something then running memory diagnostics would not hurt to run therefore rule out a memory issue.

What is this 'Windows' that you speak of ?

Memory sticks cleaned and re-seated. Memory tests passed.

Attached is a pic of what the screen looks like during the problem...

Attached Thumbnails

 

Hi,

Member in post #6 mentioned windows. That's why I responded about windows.

What about trying atl-ctrl-F1 or one of the other terminals? Your screen seems to be a rasterized issue. Try the switch to a console as suggested. Once you get to console then look at the logs to see if the issues are in Xorg.

I don't think you will be able to get to a terminal if the above is accurate but give it a try.

I've gotten screen output like you've posted from failing graphics cards. It usually begins on an intermittent basis and gets worse over time. It could also be a software/driver issue, probably due to optimus problems. If you want to eliminate a potential hardware issue before delving to deeply into software fixes, the easiest way to do that would be to reinstall windows and see if you get similar screen freezes. If you no longer have your windows recovery cd/dvd, you can try some non-ubuntu based linux livecds and see how they run. Try Mageia, Fedora or PCLinuxOS in livecd mode and see if you still get screen freezes.