problem with windows 7

OK I HAVE A WINDOWS 7 STUDIO 540S. WHEN I CLICK ON MY DESKTOP NOTHIN SEEMS TO WORK. I HAVE TO GO THROUGH PROGRAMS TO CLICK ON INTERNET EXPLORER AND ANYTHING ELSE I MIGHT WANT TO DO. IT ALMOST SEEMS LIKE THE DESKTOP IS IN A FREEZE MODE. WHAT COULD CAUSE THIS PROBLEM? ANY HELP WOULD BE APPRICIATED.