Emac Not Fully Functioning


Quite suddenly 'Finder" is not running,
when I log in there is no tool bar visible,
there are no icons visible on the desktop - Macintosh HD, Norton Utilities, Camedia, plus others were there
CD/DVD drive opens and closes but will not show - tried DVD film, Norton System works - no response.

Applications with icons in Dock still open when clicked - except Finder - Mail works, Internet Explorer works. Microsoft Word, System Preferences etc.

Any suggestions? - My level of knowledge is minimal and I have no real expertise - have had the Emac about 3 years - this is the first significant problem.