I had a similar problem recently. I was switching back and forth between Internet Explorer and "Yahoo Customized for Firefox". I found that i did not have all the same bookmarked web pages on the two different systems. Also, "bookmarks" was on the left end of one toolbar, and on the right end of the other toolbar... i couldn't find my bookmarks for awhile!

    I ended up surfing to the sites and bookmarking them all over again... there's probably an easier way to copy them.