Spent quite some time today trying to make this work. Installed Ubuntu 9.04 this AM and as expected it was not able to correctly detect the monitor resolution. Installed the latest NVidia drivers (180.44) from Synaptic package and was able to set the right resolution using "nvidia-settings" app. Before saving the configuration made sure that preview of "/etc/X11/xorg.conf" was showing as to what I had set. Restarted the system and the resolution was getting set back to "800x600". Applying a resolution using 'nvidia-settings" was still working in the session however @ logout/restart it would revert back to "800x600". Here's what all I tried and the final step that worked for me:
1) The first question I had was whether nvidia drivers were being loaded at restart or not. One of the Ubuntu knowledge base suggested adding "nvidia" to "/etc/modules" such that it gets loaded at boot time but that didn't work.
.... After many failed google searches I shifted my focus to looking at system logs for any clues......
2) checked this log file after system startup "/var/log/gdm/:0.log" and it was complaining about error loading "type2" and "freetype" modules. I wasn't sure if this was causing the "xorg.comf" to fail so I manually disabled the load of these modules in the "xorg.conf" file under the section module like below. Did a restart but still the same situation however the log "/var/log/gdm/:0.log" was not showing the error this time.
# Load "type1"
# Load "freetype"
2) Check log file "/var/log/Xorg.0.log". This log contains details on "xorg.conf" loading. Watchout for any errors in this log. In my case this log looked fine except the last line in the log file that said "[nvidia]: setting resolution 800x600". This baffled me. While the earlier lines in the log file correctly stated loading the correct resolution from 'xorg.conf', this last log line almost seemed like some another process was invoking at startup that was turning the resolution back to '800x600'. Googled around but no clue.
... Took a walk at a park nearby as my brains was about to explode.
3) Lot of sites/forums had samples of "xorg.conf" files from users whose system was working fine. Tried various of those but still no luck.
4) One of the forums post suggested this method. "System --> Preferences --> Display". Choosing that option prompts a question "It appears that your graphics driver does not support the necessary extensions to use this tool. Do you want to use your graphics driver vendor's tool instead?". if you click "yes" it takes you to the "nvidia-settings" tool. If you choose the "No" option, it allows choosing a resolution via the "Display Preferences" window. I select "No" and choose the desired resolution of "1280x1024" from the list and hit "Apply". As usual it worked in the session and voila!!!! it also worked after a restart. The resolution stayed @ "1280x1024".
Obviously there were a lot of other steps that I tried in vain but these seemed worth a note as they provide some clue as to what the issue might be. Hope this post helps.
my google searched keywords: Xorg.log nvidia 800x600, Ubuntu 9.04 resets resolution restart, ubuntu 9.04 stuck at 800x600, ubuntu 9.04 low graphics mode, ubuntu 9.04 loose settings on restart, ubuntu 9.04 lost screen resolution after restart