I tried uninstalling, cleaning up and re-installing Firefox about a hundred and umpteen times. The problems kept recurring sooner or later.
Following my mate Eddi Haskell´s advice I have know migrated to Google Chrome, and let me tell you it is really fast and bloody
E-X-C-E-L-L-E-N-T!
Somehow it even miraculously recovered all the bookmarks I thought had been lost, which saves me a lot of time and troubles.
