Comment 38 for bug 658458

@Neil: It seems that the file you attached is not the most recent one. The log files from the last execution are in /var/log/dist-upgrade. The files in the subdirectory /var/log/dist-upgrade/20110405-2234/ are those from the previous attempt on March 21.
Please attach main.log and apt.log from /var/log/dist-upgrade

I hope you have made sure that your lucid packages are up-to-date ("sudo apt-get update; sudo apt-get upgrade", try also "sudo apt-get dist-upgrade"). Some people have reported that skype has caused such error messages, try "sudo apt-get remove --purge skype". (You can reinstall skype later.)