screen background reset

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/965234

same problem shutting down the system without a previous log out. When I restart the system I always have the desktop icons overlapped as in the attached screen shot

same problem with a non-edubuntu user (administrator priviledges), but I experience screen background reset after a reboot and not after a simple log-out.

No problem if I use one of the suggested backgrounds.
N.B. the administrative user which uses a picture of mine as a background, at next reboot, cannot mount the file system where the background picture is located, I do not understand the reason why but of course I understand the reason why the background, in this case, is reset. Edubuntu user, on the contrary, correctly mounts the file system containing the background picture, but the background is set to null all the same.

I change again my background and, before having the new background displayed on my screen I see, for a very short time, the previous background displayed in the small monitor of the "Look" window. I attach the screen-shot with the current background in order you understand what I mean with "Look" window.

Some times all the file systems are correctly mounted.

Confirmed in 20120327.1 beta2 version.

I can add further details:
- change screen background for edubuntu user choosing a picture from a vfat file system located on my hard disc.
- logout from edubuntu and login as another user with administrative proviledges. This user cannot mount the vfat file system containing the background picture
- shutdown the system
- enter as edubuntu user, the screen is reset, but when I switch to the second user, the vfat file system is correctly mounted.

I attach the output of mount command when the vfat file system is NOT seen. I'll attach the mount command output of a correct situation in a next post.

sandra@edubuntu:~$ mount
/cow on / type overlayfs (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
/dev/sdb1 on /cdrom type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/loop0 on /rofs type squashfs (ro,noatime)
cgroup on /sys/fs/cgroup type tmpfs (rw,uid=0,gid=0,mode=0755)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
/dev/sda1 on /media/20E4C0C1E4C09B04 type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096)
gvfs-fuse-daemon on /home/sandra/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=sandra)
sandra@edubuntu:~$

Here are the outputs of mount and df commands for edubuntu user in a correct situation:

edubuntu@edubuntu:~$ mount
/cow on / type overlayfs (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
/dev/sdb1 on /cdrom type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/loop0 on /rofs type squashfs (ro,noatime)
cgroup on /sys/fs/cgroup type tmpfs (rw,uid=0,gid=0,mode=0755)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/edubuntu/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=edubuntu)
/dev/sda1 on /media/20E4C0C1E4C09B04 type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096)
/dev/sda6 on /media/2a8ce349-f68c-4e3c-9f20-4a58d49de7b1 type ext4 (rw,nosuid,nodev,uhelper=udisks)
edubuntu@edubuntu:~$

edubuntu@edubuntu:/media$ df
File system 1K-blocchi Usati Disponib. Uso% Montato su
/cow 1032088 544192 435468 56% /
udev 504324 4 504320 1% /dev
tmpfs 204760 880 203880 1% /run
/dev/sdb1 3893044 3767528 125516 97% /cdrom
/dev/loop0 2072832 2072832 0 100% /rofs
cgroup 511896 0 511896 0% /sys/fs/cgroup
tmpfs 511896 24 511872 1% /tmp
none 5120 0 5120 0% /run/lock
none 511896 76 511820 1% /run/shm
/dev/sda1 95594748 87327940 8266808 92% /media/20E4C0C1E4C09B04
/dev/sda6 19374208 8272252 10130028 45% /media/2a8ce349-f68c-4e3c-9f20-4a58d49de7b1
edubuntu@edubuntu:/media$

Here are the outputs of mount and df commands for the non-edubuntu user, which correctly sees the vfat file system:
sandra@edubuntu:~$ mount
/cow on / type overlayfs (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
/dev/sdb1 on /cdrom type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/loop0 on /rofs type squashfs (ro,noatime)
cgroup on /sys/fs/cgroup type tmpfs (rw,uid=0,gid=0,mode=0755)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/sandra/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=sandra)
/dev/sda1 on /media/20E4C0C1E4C09B04 type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096)
/dev/sda6 on /media/2a8ce349-f68c-4e3c-9f20-4a58d49de7b1 type ext4 (rw,nosuid,nodev,uhelper=udisks)
sandra@edubuntu:~$ df
File system 1K-blocchi Usati Disponib. Uso% Montato su
/cow 1032088 540208 439452 56% /
udev 504324 4 504320 1% /dev
tmpfs 204760 884 203876 1% /run
/dev/sdb1 3893044 3767528 125516 97% /cdrom
/dev/loop0 2072832 2072832 0 100% /rofs
cgroup 511896 0 511896 0% /sys/fs/cgroup
tmpfs 511896 12 511884 1% /tmp
none 5120 0 5120 0% /run/lock
none 511896 152 511744 1% /run/shm
/dev/sda1 95594748 87327940 8266808 92% /media/20E4C0C1E4C09B04
/dev/sda6 19374208 8272252 10130028 45% /media/2a8ce349-f68c-4e3c-9f20-4a58d49de7b1
sandra@edubuntu:~$

/media/20* contains an UBUNTU 11.10 system
/media/2a* contains a windows xp system