plasma-desktop crashed with SIGSEGV in notify_helper()

lsb_release -rd
Description: Ubuntu 12.04
Release: 12.04

apt-cache policy plasma-desktop
plasma-desktop:
  Installiert: 4:4.8.0b-0ubuntu5
  Kandidat: 4:4.8.0b-0ubuntu5
  Versionstabelle:
 *** 4:4.8.0b-0ubuntu5 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main amd64 Packages

plasma-desktop crashed on startup

ProblemType: Crash
DistroRelease: Ubuntu 11.11
Package: plasma-desktop 4:4.8.0b-0ubuntu5
ProcVersionSignature: Ubuntu 3.2.0-18.28-generic 3.2.9
Uname: Linux 3.2.0-18-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.94-0ubuntu1
Architecture: amd64
Date: Mon Mar 5 08:52:06 2012
Disassembly: => 0x0: Cannot access memory at address 0x0
ExecutablePath: /usr/bin/plasma-desktop
ProcCmdline: /usr/bin/plasma-desktop --nocrashhandler
ProcEnviron:
 LANGUAGE=de_DE:en
 PATH=(custom, user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x0: Cannot access memory at address 0x0
 PC (0x00000000) not located in a known VMA region (needed executable region)!
SegvReason: executing NULL VMA
Signal: 11
SourcePackage: kde-workspace
StacktraceTop:
 ?? ()
 notify_helper (e=0x7fff544344f0, receiver=0x395d5e0, this=0x111ced0) at kernel/qapplication.cpp:4555
 QApplicationPrivate::notify_helper (this=0x111ced0, receiver=0x395d5e0, e=0x7fff544344f0) at kernel/qapplication.cpp:4527
 QApplication::notify (this=0x10ceb00, receiver=0x395d5e0, e=0x7fff544344f0) at kernel/qapplication.cpp:4416
 KApplication::notify (this=0x10ceb00, receiver=0x395d5e0, event=0x7fff544344f0) at ../../kdeui/kernel/kapplication.cpp:311
Title: plasma-desktop crashed with SIGSEGV in notify_helper()
UpgradeStatus: Upgraded to oneiric on 2011-10-10 (146 days ago)
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