In case i forget again…

Problem on Ubuntu 10.04 (Lucid Lynx) x64:

$ sudo aptitude update
Hit http://security.ubuntu.com lucid-security Release.gpg
Ign http://security.ubuntu.com/ubuntu/ lucid-security/main Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/restricted Translation-en_US
...
Hit http://us.archive.ubuntu.com lucid-updates/multiverse Sources
Reading package lists... Done
Segmentation fault

Solution:

$ sudo rm /var/cache/apt/*.bin
$ sudo apt-get update

Aptitude should now work again.