If it's an old card installing version 173 from Nvidia may help to stabilize your system. Performance is not great though, but it helps with my 12.10 version. Hope 13.04 will be better.
Verzonden vanaf mijn BlackBerry®-toestel

-----Original Message-----
From: akI <email address hidden>
Sender: <email address hidden>
Date: Sun, 14 Apr 2013 05:50:41 
To: <email address hidden>
Reply-to: Bug 1033263 <email address hidden>
Subject: [Bug 1033263] Re: Ubuntu 12.04 freezes with nvidia drivers

I can confirm this on 12.04 LTS and also on 12.10 with a very fresh
install of ubuntu.

Its absolutely regardless which nvidia driver i activate (current, current-updates, experimental) the desktop freezes randomly with ativated nvidia driver. 
Sometimes the system freezes complete, desktop, mouse and keyboard are stocked. 
Sometimes only the keyboard and desktop freezes. and i can move the cursor but are not able to make the dekstop response do any kind of mouse interacting.

If i change back to NV driver the system runs stable.

Also this only happens the very first boot on the day. If i restart my system i can run it for hours without any problem.
For now i have deactivated the nvidia drivers, hopefully someone can fix this.

I also can confirm (but im not sure) that this must have to do with
unity as im running a dualboot system with 12.04 LTS and Ubuntu Studio
12.10. On Ubuntu Studio which uses XFCE the system runs stable with the
latest nvidia driver activated.

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report.
https://bugs.launchpad.net/bugs/1033263

Title:
  Ubuntu 12.04 freezes with nvidia drivers

Status in “nvidia-graphics-drivers” package in Ubuntu:
  Confirmed

Bug description:
  After activiting Nvidia drivers complete freezes (only hard reset
  works). Mouse cursor moves, all else seems to come to an instant halt.

  Hardware: Acer Aspire 7520, Geforce 8400m G (shared memory).

  (Re)installing Nouveau drivers 'solves' the problem. Newer Nvidia
  drivers from PPA unsucceslful as well (same problem).

  Laptop works like a charm with 11.10 and nvidia drivers.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: linux-image-3.2.0-27-generic 3.2.0-27.43
  ProcVersionSignature: Ubuntu 3.2.0-27.43-generic 3.2.21
  Uname: Linux 3.2.0-27-generic x86_64
  NonfreeKernelModules: nvidia
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
  ApportVersion: 2.0.1-0ubuntu11
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  hein       1932 F.... pulseaudio
  CRDA:
   country NL:
    (2402 - 2482 @ 40), (N/A, 20)
    (5170 - 5250 @ 40), (N/A, 20), NO-OUTDOOR
    (5250 - 5330 @ 40), (N/A, 20), NO-OUTDOOR, DFS
    (5490 - 5710 @ 40), (N/A, 27), DFS
  Card0.Amixer.info:
   Card hw:0 'NVidia'/'HDA NVidia at 0xf0880000 irq 21'
     Mixer name	: 'Realtek ALC268'
     Components	: 'HDA:10ec0268,10250126,00100003 HDA:14f12c06,10250126,00100000'
     Controls      : 26
     Simple ctrls  : 14
  Date: Sun Aug  5 20:48:28 2012
  HibernationDevice: RESUME=UUID=8ec5ad0a-4378-4d68-a4d4-d35c9b66570e
  InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
  MachineType: Acer Aspire 7520
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=nl_NL.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 VESA VGA
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-27-generic root=UUID=613ca040-8bae-4af8-8b6a-33d7d98e49a7 ro quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.2.0-27-generic N/A
   linux-backports-modules-3.2.0-27-generic  N/A
   linux-firmware                            1.79
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 07/12/2007
  dmi.bios.vendor: Acer
  dmi.bios.version: V1.05
  dmi.board.name: Fuquene
  dmi.board.vendor: Acer
  dmi.board.version: N/A
  dmi.chassis.type: 10
  dmi.chassis.vendor: Acer
  dmi.chassis.version: N/A
  dmi.modalias: dmi:bvnAcer:bvrV1.05:bd07/12/2007:svnAcer:pnAspire7520:pvrV1.05:rvnAcer:rnFuquene:rvrN/A:cvnAcer:ct10:cvrN/A:
  dmi.product.name: Aspire 7520
  dmi.product.version: V1.05
  dmi.sys.vendor: Acer

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