Firefox is aging?

Apparantly Firefox is keep losing my location history like an old man.

I found that sometimes when I start Firefox, nearly all history is got! I experience that on both a Windows 2000 and Windows XP machines. That's weird.

How to reproduce the bug? I don't know. Just keep using Firefox, when you find that it doesn't auto-complete your recently visited URLs, you know it happens again.

Fortunately other stuffs like cookies are still there...