I installed jre and unity won't work anymore

[Charles Ford]

Recent update to 12.10.
Libre Office was complaining about no jre, so I installed jre.
After reboot, unity would show up and then disappear. No bar at the top and no sidebar. Keyboard shortcut wouldn't bring up terminal.

Description: Ubuntu 12.10
Release: 12.10

java-common:
  Installed: 0.43ubuntu3
  Candidate: 0.43ubuntu3
  Version table:
 *** 0.43ubuntu3 0
        500 http://us.archive.ubuntu.com/ubuntu/ quantal/main i386 Packages
        100 /var/lib/dpkg/status

I can boot up in Gnome, and Libre Office no longer complains.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: java-common 0.43ubuntu3
ProcVersionSignature: Ubuntu 3.5.0-24.37-generic 3.5.7.4
Uname: Linux 3.5.0-24-generic i686
ApportVersion: 2.6.1-0ubuntu10
Architecture: i386
Date: Sat Feb 16 15:03:53 2013
Dependencies:

InstallationDate: Installed on 2013-01-15 (32 days ago)
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: java-common
UpgradeStatus: Upgraded to quantal on 2013-02-15 (1 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.