Firefox

Sometimes, firefox fails to load, giving an error such as File:Http://kb.mozillazine.org/images/CloseFX msg.png.

The solution is to delete the files lock and .parentlock in the afflicted user's profile directory. The profile name is a garbled mess, for example looking in a location such as ~/.mozilla/firefox/fdsfh385.default/ should show the files.

Typically, this is caused by a machine crash or strange profile conflicts from logging onto multiple machines at once and running firefox multiple times.