LOL hey I'm 55, but my kids started out as 8 & 10 yr olds long ago -with garage sale computers & parts so i learned along with them.
went to many many G sales back in those days...
still have some of those old parts in the basement...

I thought you double checked to make sure they got copied onto the flash drive??
or you just saw the folder name and thought it had the favorites in it???
I always open the folder or file on the flash drive to make sure what I wanted is actually there, sorry if I didn't explain that completely.

That is strange about the FF issues.
What version do you have - 6.2? It's the newest one.

So FF works fine online but won't do the bookmarks/favorites...odd
FIREFOX HAS STOPPED WORKING"
that error message is odd too.