On my system, users' home directories are mounted by NFS and aren't accessible by root. This seems to upset aptitude if I run "aptitude update" when su'ed to root in my home directory: wraith:/home/bjh21# aptitude update Hit http://www-uxsup.csx.cam.ac.uk testing Release.gpg Hit http://www-uxsup.csx.cam.ac.uk testing Release Hit http://www-uxsup.csx.cam.ac.uk testing/main Packages/DiffIndex Hit http://www-uxsup.csx.cam.ac.uk testing/contrib Packages/DiffIndex Hit http://www-uxsup.csx.cam.ac.uk testing/non-free Packages/DiffIndex E: Unable to change to /home/bjh21/ - chdir (13: Permission denied) E: Couldn't clean out list directories I can't see that aptitude has any reason to chdir into my home directory, so it really shouldn't fail when that turns out to be impossible. pkgAcquire::Clean(std::string). I've not looked at the source to see how easy it would be to fix.