Corrupt background image after suspend

[Adelina-Roxana Suhani]

Steps to reproduce:
1. After system boot login as an user in a graphical (Unity) session.
2. Switch account and log in as a different user (in a default Unity this can be done by clicking the user name in the top right corner and clicking "Switch User Account" from the drop-down menu, select another user from the login screen, insert password and hit enter).
3. The second user suspends the computer (in a default Unity this can be done by clicking the power icon and then "suspend" option from the drop-down menu).
4. After resuming the system, at login screen switch to the first user(in a default Unity this can be done by clicking "switch user" button, select user id, insert password, hit enter).

Expected result:
The graphical environment should be the same as it was before suspension.

Actual result:
After logging in the background image is corrupted (see screenshot).
Also while selecting portions of the screen with the mouse the background image becomes visible but returns to it's state when the mouse button is released.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubuntu-desktop 1.267.1
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic-pae 3.2.30
Uname: Linux 3.2.0-32-generic-pae i686
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: i386
Date: Fri Mar 15 17:20:00 2013
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-meta
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.