I get the following message when going online with Firefox: "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem." I've followed all the prompts to restart the computer, refresh the computer, delete the favicons.sqlite and places.sqlite and it won't allow me to delete them. This happened yesterday as well. Yesterday I could delete those files and everything was restored. But today I can't get it to work.