Inspiron 660 Start-up Problem

I am experiencing semi-frequent start-up problems with my Dell Inspiron 660 desktop. After entering my password on the Start-up Screen I get a spinning circle with "Welcome". I then get a completely black screen with a mouse pointer. I am unable to proceed further and have to press Ctrl-Alt-Delete to Sign Out, then hold in my power button to shut down the system. Usually I am successfully when I start the desktop a second time. Any information on what is causing the problem and suggestions to fix it would be appreciated.