Handy Computer Tips

• If Firefox won't start: Let's say you get a message like either of:
  (Windows) "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system." or
  (Mac OS X) "A copy of Firefox is already open. Only one copy of Firefox can be open at a time."
  
  You need to find
  ".parentlock" (OS X), or
  "parent.lock" (Windows) or
  "lock" and/or ".parentlock" (Linux),
  delete the file, and away you go.
  See also here.

• To prevent Windows XP (and others) from automatically rebooting after downloading a "reboot-required" update (patch), do this (found here):
  1. Click the Start button, then "Run...".
  2. In the dialog box, type "gpedit.msc" and hit enter.
  3. Once the screen comes up click the + next to "Local Group Policy",
  4. then "Computer Configuration"
  5. then "Administrative Template"
  6. then click on the "Windows Updates" folder.
  7. In here you will find a bunch of different variables. If you click on them in the right pane there should be some definitions of what each one does. The key we are looking for is "No auto-restart for scheduled Automatic Updates Installations". Right click on that value and hit properties.
  8. Now click on Enabled, than hit "Apply" and "Ok".
  9. Now close the Console1 window. It will (may) prompt you to save, choose "Yes" and than "Save".
  10. Now that you have saved the settings a reboot is necessary for the policy to take effect.