[apport] beryl crashed with SIGSEGV in _nv000042gl()

Binary package hint: beryl-manager

After rebooting the system, once logged into gnome with beryl-manager running with beryl-core or beryl on backend, if I do a alt+ctl+F1, and then try to come back to gui with alt+ctl+F7, it gives a black screen with just mouse. I cant even kill X at that time. Only way I could find to come back is hard shut down system (pressing and holding power button).
I have Nvidia GeForce MX 4000 card.

ProblemType: Crash
Architecture: i386
Date: Mon Mar 19 00:39:17 2007
DistroRelease: Ubuntu 7.04
ExecutablePath: /usr/bin/beryl
Package: beryl-core 0.2.0~0beryl1
PackageArchitecture: i386
ProcCmdline: beryl --skip-gl-yield
ProcCwd: /home/renjoy
ProcEnviron:
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=en_IN
 SHELL=/bin/bash
Signal: 11
SourcePackage: beryl-core
StacktraceTop:
 ?? () from /usr/lib/libGLcore.so.1
 ?? ()
 ?? ()
 ?? ()
 _nv000042gl () from /usr/lib/libGLcore.so.1
Uname: Linux renjoy-desktop 2.6.20-11-generic #2 SMP Thu Mar 15 08:03:07 UTC 2007 i686 GNU/Linux
UserGroups: adm admin audio cdrom dialout dip floppy lpadmin netdev plugdev powerdev scanner video