Had the same problem. The problem first appeared when adding a repo to upgrade from etch to lenny. Removing everything and recreating empty directories in /var/cache/apt didn't help. Removing everything and recreating empty directories in /var/lib/apt didn't help either. The measure that helped was to create /etc/apt/apt.conf with only the following line: APT::Cache-Limit "20000000"; Regards, -i.