I've started experiencing a strange problem with Firefox 1.0. After running it for a while, the bookmark toolbar disappears replaced by a small set of double arrows that when clicked opens the same toolbar as a vertical menu. When I exit the browser and open it again, everything is fine. I've googled, but haven't found anything (admittedly, I have not spent a lot of time searching yet). The OS is Win2000 Pro. I have not seen this problem in previous releases. Any ideas?