I have an Inspiron 8400 that will not not boot up.  It never even gets to the DOS prompt.  It beeps in a pattern of 1-3-2 and the code lights on the back have A and B in yellow and C and D in green.  I know that the beep code and the code light combination have meaning but I have not been able to find a guide to tell me.  I dont mind looking things up myself.  I am having trouble finding where to start.  All help appreciated.