Redlemon

OK, check out this bug and see if it describes your situation (putting the bookmarks in a location that is not always available):
Bug 251692 - bookmarks file is overwritten by an empty file in a certain mount sequence
(and similarly, Bug 259801 - start of firefox from samba network drive deletes existing bookmarks.html)

Otherwise, there's
Bug 249150 - Bookmarks file is overwritten (deleted) randomly
which doesn't really have much information in it.

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