Firefox Bookmarks question

Have Firefox 3.0.6 and never had trouble with Bookmarks before, but now something is screwy.

First, I wonder if there is a limit on the number of bookmarks allowed?

I have quite a few, but create folders as much as possible to contain all relevant ones. Yet the last few times I tried to “Bookmark This Page” it did not save it. Tried several different sites.

So, went to the end where recent bookmarks were, and deleted quite a few. Then I created a new folder for several others and dragged them into it . They were all there, but the next time I opened Firefox, all the deleted bookmarks returned, but the new folder was not. Tried this a couple times more with same result. Used both the drop-down Bookmark menu and the CTRL B list, same thing.

Anybody have any idea what is going on. Am I missing some way to “save” these? Never had to before; deleted ones vanished and new ones stayed there.

Sorry for the bump, would like add another question. I went to the FF help files and found a lot of things that were supposed to correct this not-uncommon problem, but none of them worked, including exporting and importing back the bookmarks.HTML.

Does anybody know if I uninstall the 3.0.6 version and re-install the previous version whether that will cause any problems? And whether it will preserve the existing bookmarks?

I have to do something, and am ready to try that, but am concerned it may not work or work properly.