Screen corruption problems: more data

[Tim Hunt]

> Tim Hunt wrote:
> 
>> Summary of problem:
>>
>> I just tried installing Ubuntu (Hoary preview) for the first time, and 
>> it all worked except that the screen display was corrupted. I have 
>> never successfully installed Linux.
>>
>> I have now downloaded and tested both the Warty live CD, and the new 
>> Hoary release candidate live CD. The Warty one worked perfectly (I 
>> thought I remembered that but have tested again), but the Hoary RC one 
>> does not work, in the same way that my failed install does not work.
>>
>> What can I do to diagnose the problem? I have already posted details 
>> about my hardware and Xorg.conf file from my install.

Christoph Georgi wrote:

> Have a look at the xorg.0.log in /var/log. That might state the error 
> that occurs when x starts..

The only error in there is:

(EE) R128(0): No DFP detected

According to my google searches, several other people have get this 
error with a variety of symptoms, none of which exactly match mine, and 
I did not see anything that looked like a solution I could try. Other 
people were seeing blank screens, or X refusing to start altogether.

What I see is a slightly corrupted screen display which I will try to 
describe: Some bits of the screen appear absolutely fine and in the 
right place, but some vertical stripes of the screen are scrambled up 
and appear in the wrong place (that is, it is clearly a perfectly 
accurately rendered part of the screen, it is just shifted sideways from 
where it ought to be), and some of those shifted bits are actually 
duplicates of each other, or of correct bits. There is a small amount of 
noise on top of all that, particularly at the boarders between strips.

Changing the screen resolution or refresh rate does no help, you get the 
same sort of corruption, though the corrupted bits are in different 
places, which is just enough to let me navigate through the login screen 
and to the reboot controls, so I can get back to Windows to send these 
emails without having to resort to the power button. So at least at some 
level, under the corruption, X is working, and the widgets are there and 
respond to the mouse and keyboard.

The other thing I gleaned from Google is that the "DFP" in the error 
stands for "digital flat panel". I am a bit confused by that. My monitor 
(which is indeed a TFT flatscreen) plugs into my graphics card using a 
d-sub cable. In fact the graphics card is so old, that it does not even 
have a DVI-out connector. So how can X tell what sort of screen is the 
other end of the cable? and how can it think that it is missing while I 
can see stuff on the screen?

The whole xorg.0.log file is quite long, so I won't attach it here. If 
anyone fancies taking a look, it is at http://timhunt.me.uk/junk/Xorg.0.log

Thank you very much for your help.

Tim.