A little more info... It seems that "browser.fixup.alternate.enabled" is no longer an available setting in about:config. Not sure if its removal was intentional or something missed in the coding.

You should be able to use Ctrl+Enter to force a fixup. Note that this may not work if you specify the https:// protocol.

• about:config => browser.urlbar.ctrlCanonizesURLs => true

Neither suggestion worked.

I'll throw a new twist into this. I installed regular firefox, imported my bookmarks and tested... Same result... firefox does not add the prefix or suffix when enter is pressed and still get the "We can’t connect to the server at craigslist. Did you mean to go to www.craigslist.com? message.

A little more info.... Pressing control+enter will add the prefix and suffix to the website. From what I've read, that's the fix if private browsing is enabled. I've looked in the privacy and security section and don't see anywhere that private browsing is activated, nor do I see the little private browsing icon anywhere on the status bar...