Weird corruption with Xephyr

[Yan Seiner]

I'm seeing this rather weird corruption with Xephyr.  The system is 
running Debian Lenny  with a custom 2.6.27.4 kernel.  I am running 
Xephyr 1.5.3.  I've captured an image of this here:

<http://seiner.com/images/imga0018.jpg>

This happens after some time - can be minutes, hours or days.  The 
screen just flickers and then wraps right a lot and down very slightly.  
You can see it in the poor quality image above (sorry for the poor 
quality image.  That was shot with a handheld video camera).  This has 
happened on 2 of the 3 Xephyr servers so far.

It doesn't appear to be video driver related; I've been running various 
versions of nvidia binary blob driver for a while now.  I have updated 
Xephyr from 1.5.1, and the problem appears since then.  A second 
machine, which has the same video hardware, and still runs 1.5.1, 
doesn't exhibit the problem.

I've been through all the logs I can find, and there is nothing at all 
out of the ordinary in any of them.

I've considered hardware failure, but the problem occurs on both video 
cards in the system, so it's unlikely that both would fail at the same 
time in the same way.

Is there some way to get Xephyr to generate verbose logs to try and 
capture this?

Any other suggestions?

--Yan