Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Go to Firefox > History > Clear recent history or (if no Firefox button is shown) go to Tools > Clear recent history.
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the Clear now button.

Further information can be found in the Clear your cache, history and other personal information in Firefox article.

Did this fix your problems? Please report back to us!

Already tried it, Google still gives this weird code.

Seems a good ole re-boot sorted it, still odd error mind.

Tobbi's solution worked for me immediately after I did it and I thought the problem was completely fixed, but apparently not because the next morning the problem came back and it's been like that all day.

cor-el's suggestion here seems to work for most people: https://support.mozilla.org/en-US/questions/930473#answer-346039