crash when 'searching' from URL box

beata@thylacine:~$ midori
.....
midori: /build/buildd/cairo-1.10.2/src/cairo-surface.c:1287: cairo_surface_set_device_offset: Assertion `status == CAIRO_STATUS_SUCCESS' failed.
Aborted

I was using midori a while, then I typed 'launchpad.net' into the URL box and it crashed.
It isn't entirely consistant. Also has crashed with:

beata@thylacine:~$ midori

GLib-ERROR **: /build/buildd/glib2.0-2.30.0/./glib/gmem.c:378: overflow allocating 2147483648*4 bytes
Trace/breakpoint trap

when chusing "Show last tabs without loading" from the crash dialog; and:
beata@thylacine:~$ midori
Segmentation fault

after chusing "Discard old tabs" and typing 'launchpad.net' into the URL box.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: midori 0.4.0-2
ProcVersionSignature: Ubuntu 3.0.0-16.29-generic 3.0.20
Uname: Linux 3.0.0-16-generic i686
ApportVersion: 1.23-0ubuntu4
Architecture: i386
Date: Fri Feb 24 23:24:35 2012
EcryptfsInUse: Yes
InstallationMedia: Xubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111011)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: midori
UpgradeStatus: No upgrade log present (probably fresh install)