First try clearing your cookies. Go to ->Options ->Options ->Privacy ->"Clear your recent history" ->Select "Everything" from the time range. ->then "Clear Now"

If that doesn't work, try this. ->Options ->Options ->Advanced ->"Network" tab ->Under "Connection" hit the "Settings" button. ->select "No proxy" and hit "OK" ->Restart Firefox

Hope that helps.

Try clearing the cache as well.

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"