dpkg crashed causing inoperable synaptic

Binary package hint: file-roller

new install of Ubuntu 8.04
E: dpkg was interrupted, you must manually run 'dpkg --configure -a' to correct the problem.
E: _cache->open() failed, please report.

HOW DO i DO THIS??????????????
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ProblemType: Bug
Architecture: i386
Date: Sun Jun 1 23:46:15 2008
DistroRelease: Ubuntu 8.04
ExecutablePath: /usr/bin/file-roller
Package: file-roller 2.22.2-0ubuntu1
PackageArchitecture: i386
ProcEnviron:
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: file-roller
Uname: Linux 2.6.24-17-generic i686