When ls -l is run on a catalog containing catalog(s) owned by users no
longer existing on the system, ls hangs and the memory usage of the job
grows until linux hangs because of high load.

Example:

The catalog /home contains the catalog mm owned by the user marius, who
were removed from the system earlier today.

... /home > ls -l

listes the catalogs before mm in the alphabet, then ls hangs.

The command

... /home > ls -l mm

works fine, it gives the number of the now removed owner as owner of the
catalog.

The problem also is created by ftp users doing a long ls.