Comment 42 for bug 650539

After spending some time working with my two monitors in TwinView mode, i realized that it's not a solution - it's definitely not a replacement for Xinerama, so... I decided to get that Xinerama mode that worked for me (in 10.04) before i had updated to 10.10 back :)

As Laurent mentioned above, a possible workaround to fix that issue is to rollback to old versions of some packages...

Actually, the only packages i reverted were: xorg, xserver-xorg, xserver-xorg-core, xserver-xorg-input-evdev, xserver-xorg-input-mouse, xserver-xorg-input-vmmouse, xserver-xorg-video-nv (i have installed versions from 10.04 via dpkg). Once reverted, those seem to work fine in Xinerama mode and latest nVidia drivers included in 10.10 (that is, 260.10.06).

To get those packages, do the following:

Open terminal and execute the following command (will download those packages into tmp dir and install them, you'll have to input root-pass to confirm installation):

mkdir /tmp/xpackages && cd /tmp/xpackages && wget http://launchpadlibrarian.net/43485102/xorg_7.5%2B5ubuntu1_i386.deb http://launchpadlibrarian.net/43485099/xserver-xorg_7.5%2B5ubuntu1_i386.deb http://launchpadlibrarian.net/52260944/xserver-xorg-core_1.7.6-2ubuntu7.3_i386.deb http://launchpadlibrarian.net/42588308/xserver-xorg-input-evdev_2.3.2-5ubuntu1_i386.deb http://launchpadlibrarian.net/36552692/xserver-xorg-input-mouse_1.5.0-1_i386.deb http://launchpadlibrarian.net/45024060/xserver-xorg-input-vmmouse_12.6.5-4ubuntu2_i386.deb http://launchpadlibrarian.net/37545335/xserver-xorg-video-nv_2.1.15-1ubuntu3_i386.deb && sudo dpkg -i *.deb

There's a drawback though: after installing those mentioned above packages via dpkg lot of "broken" packages (a bit more than 30 in my case) appears - namely, all xserver-xorg-input-* and all xserver-xorg-video-*...

Here's how you fix that: open Synaptic and use "Edit -> Fix Broken Packages" feature, then apply changes - it will notify you it wants to remove lot of packages - mostly those broken ones and probably few more, but seems to not touch anything important (in my case it listed "xbmc-standalone" only) - anyway, you may want to log those packages to re-install them later.

Now, as you have removed broken packages, you must reinstall downloaded xserver/xorg (from 10.04) again as they were removed too. Just run the following command in console:

cd /tmp/xpackages && sudo dpkg -i *.deb

Now you may open Synaptic again and re-install those removed packages (like xbmc, etc.) that you logged earlier.

After that you should have working and clean system! ;)

The last thing is: protect those old packages from auto-updating (otherwise you'll get this X-crash-issue back).

In Synaptic, select each of those packages you have reverted and choose "Package -> Lock Version" for each of them.

Now you can update whenever you wish (when update-manager notifies you about fresh updates) and all packages except those with locked versions will be updated as usually.

That's it. Sorry if it looks messy, but it worked for me, so i decided to share my solution.

Hope this helps someone! ;)