Blank blue screen only

Hi all.  Help please.  Upon computer start up...the ctrl, alt, delete demand pops up, then the logon screen, but then just a blank blue screen after that.  There is no taskbar button, start button or even icons.  I don't know what to do?  I don't even see the BIOS start up screen before the ctrl, alt, delete screen.  Please help.  Thank you so much.