Firefox downloading problem

Recently my firefox explorer has had one major probblem, ANYTHING requiring the downloads window to come up, will not download. No error messages, and i can open the download box manually, but nothing will download, this is drving me insane, im having to use IE for everything. I have reinstalled it, and deleted the progam files file it leaves behind, but it still wont download anything. I have no extensions, what the heck is wrong? I also cleared cookies.

I reccomend you try the Flashgot extension, or a download manager.