nautilus error report when login (ctrl alt back)

This bug appears every time I log out using ctrl alt and backspace. An error window appears at the desktop stating "nautilus cannot be started" or something very similar. In addition the background picture is not displayed and replaced by black (not my default colour). This is more annoying than anything else. I installed Gutsy 7.10 but upgraded to Hardy alpha via the terminal.

ProblemType: Crash
Architecture: i386
CrashCounter: 1
Date: Mon Jan 28 15:37:32 2008
DistroRelease: Ubuntu 8.04
ExecutablePath: /usr/bin/compiz.real
NonfreeKernelModules: nvidia
Package: compiz-core 1:0.6.99+git20080102-0ubuntu5
PackageArchitecture: i386
ProcCmdline: /usr/bin/compiz.real --ignore-desktop-hints --replace --loose-binding --sm-client-id default0 ccp
ProcCwd: /home/matthew
ProcEnviron:
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
Signal: 11
SourcePackage: compiz
Stacktrace:
 #0 0x08055a4d in ?? ()
 #1 0x0807d8f0 in ?? ()
 #2 0x00000003 in ?? ()
 #3 0x000000ef in ?? ()
 #4 0x00000000 in ?? ()
StacktraceTop:
 ?? ()
 ?? ()
 ?? ()
 ?? ()
 ?? ()
Title: compiz.real crashed with SIGSEGV
Uname: Linux matthew-desktop 2.6.24-5-generic #1 SMP Thu Jan 24 19:45:21 UTC 2008 i686 GNU/Linux
UserGroups: adm admin audio cdrom dialout dip floppy lpadmin netdev plugdev powerdev scanner video