In short: about 50% of the time I have a screwed up monitor setup after reboot. About 50% it is totally correct.

Now the longer version:
I updated my machine from 9.04 to 10.04 (via 9.10). At first I run into some monitor problems (I have a 3-monitor setup) because of the known bug in the new xserver driver for xinerama. This messes up behaviour if the mouse goes either left or above the screen number 0, i.e. I had to make my left-most monitor screen 0.
Everything worked out fine finally, I got my 3-monitor setup back with xinerama enabled to get one big desktop streched over 3 screens.

Now the fun part:
Every time I start up my machine only one of the 3 monitors gets a signal and is woken up: it only recognizes the left-most monitor (screen 0) and crams all the desktop stuff into this one screen. If I go into nvidia settings I only see one physical device although all 3 are connected and have power. When I look into the xorg.conf I can still see my old setup with 3 devices, 3 screens, xinerama active etc... But I was totally unable to get 3 montitors to work. (I tried unplugging monitors, reconfiguring whole nvidia setup, ...)

But it gets even better:
When I restart my machine (i.e. choose the restart option from the Ubuntu menu) it shuts down and tries to restart. The restart then gets stuck after showing the Ubuntu splash screen with the 'loading bar' (the moving dots thingy) and I am forced to kill the machine by cutting power. But after the power cut the machine boots up normally and suddenly I get my 3 monitor setup back up working. That is until the next time I shut down and start up, where it all starts over again and I only have one monitor... (see above)

I really have a hard time seeing where the error is. It must be that the restart boot somehow differs from the 'normal' boot. But the fact that it gets stuck and I need to cut power which then basically triggers a 'normal' boot does not really support this theory...

My setup (please tell me if you need further info):

• 3 monitors as 3 screens as one desktop (with xinerama)
• 2 nvidia cards where screen 0 and 1 are on card 0 and screen 2 is on card 1
• Ubuntu 10.04 Lucid Lynx (updated from 9.10, 9.04, ....)

I would appreciate every idea on the subject, at the moment I really don't have any clue what to do...