When I click on the Safari icon a grey questionmark appears on top of it and Safari does not open.   The same thing happened with Word (excel works fine) and, to make matters worse, when I tried to open some docs in Finder, they would only open as text files.  Now they do not look like word files when listed in finder - their icons are blank so it feels like I have lost the formatting at least, forever!   Does anyone have any idea what has caused this and how I can put...