To enable cookies when using FireFox:
  1. Open an Internet window and click Tools > Options
  2. Click the Privacy tab
  3. Click "Accept cookies from site" and "Accept 3rd party cookies
    then in the drop-down choice select "Keep until they expire"

 
 
Firefox 2.x
Firefox defaults to accept all cookies. To check cookie settings:

1.Click on Tools.
2.Click on Options.
3.Click on Privacy.
4.Make sure that "Accept cookies from sites" is selected.
5.Click on OK.

Firefox 1.x
Firefox defaults to accept all cookies. To check cookie settings:

1.Click on Tools.
2.Click on Options.
3.Click on Privacy, if the Privacy panel is not open.
4.Click on the plus (+) sign to the left of Cookies.
5.Make sure that "Allow sites to set cookies" is checked.
6.Click on OK.