firefox crashed with signal 5 in __pthread_mutex_unlock_usercnt()

[George Hein]

Binary package hint: firefox-3.5

Using a 9.04 Ubuntu upgraded to 9.10 with latest updates. This has been happening since an update several days ago.
Firefox has been useless, exiting as third tab is opened and sometimes immediately.

 (I had to go back to 9.04 on another partition for normal usage, but will continue testing 2x a week --- however, before last major changes to Firefox all went fairly well with the 9.10 version. Note that earphones also no longer work since some major changes)
Lenovo-IdeaPad-Y530.

ProblemType: Crash
Architecture: i386
CrashCounter: 1
Date: Sat Aug 15 11:34:46 2009
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/lib/firefox-3.5.2/firefox
Package: firefox-3.5 3.5.2+nobinonly-0ubuntu2
ProcCmdline: /usr/lib/firefox-3.5.2/firefox --sm-config-prefix /firefox-A2C8sw/ --sm-client-id 107f41c3645dcf6723124920925573437300000056500029 --screen 0
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-5.24-generic
Signal: 5
SourcePackage: firefox-3.5
StacktraceTop:
 ?? () from /usr/lib/libgdk-x11-2.0.so.0
 ?? () from /usr/lib/libbonoboui-2.so.0
 ?? ()
 ?? ()
 __pthread_mutex_unlock_usercnt ()
Title: firefox crashed with signal 5 in __pthread_mutex_unlock_usercnt()
Uname: Linux 2.6.31-5-generic i686
UserGroups: adm admin cdrom dialout disk grp lpadmin plugdev sambashare