Ubuntu kernel 2.6.32-20 doesn't boot

[Dean]

Binary package hint: firefox

I used Ubuntu 10.04 upgrade from Ubuntu 9.04. I do regular update. When I update to kernel 2.6.32-20, it doesn't boot anymore.
My computer is Acer Aspire 4710. It works well till kernel 2.6.32-19.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: firefox 3.6.3+nobinonly-0ubuntu2
ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
Uname: Linux 2.6.32-19-generic i686
Architecture: i386
Date: Mon Apr 12 16:04:47 2010
FirefoxPackages:
 firefox 3.6.3+nobinonly-0ubuntu2
 firefox-gnome-support 3.6.3+nobinonly-0ubuntu2
 firefox-branding 3.6.3+nobinonly-0ubuntu2
 abroswer N/A
 abrowser-branding N/A
InstallationMedia: Edubuntu 10.04 "Lucid Lynx" - Alpha i386 (20100114.1)
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: firefox