perl-libxml-libxml fails on upgrade hardy to intrepid

Binary package hint: update-manager

Used alternative install disk for upgrade (script in root of cdrom). After failing to update perl-libxml-libxml, the upgrade continued. However, the upgrade process terminated abnormally on failing to update the update manager, with an error message that system might be unusable. The system was usable on restart, but needed some packages installed manually.
0. cdrom removed from repository list, and network repositories enabled (main, restricted, universe, multiverse)
1. perl-libxml-libxml was marked broken and could not be fixed - it had to be removed completely with synaptic
2. perl-libxml-libxml was then installable from synaptic
3. update manager was then installable from synaptic
4. samba was updated in the upgrade, but remote file systems were not mountable using mount -a
5. smbfs had to be installed using apt-get, then mount -a worked correctly
6. the rest of installed packages were then updated from network repositories

ProblemType: Package
Architecture: i386
DistroRelease: Ubuntu 8.10
ErrorMessage: ErrorMessage: SystemError in cache.commit(): E:Sub-process /usr/bin/dpkg returned an error code (1)

Package: update-manager 1:0.93.32
PackageArchitecture: all
SourcePackage: update-manager
Title: package update-manager 1:0.93.32 failed to install/upgrade: ErrorMessage: SystemError in cache.commit(): E:Sub-process /usr/bin/dpkg returned an error code (1)
Uname: Linux 2.6.24-21-generic i686