Can't get on my notebook!! HELP!

Hello, I have a year old Dell Inspiron 2650 with Intel Celeron 1.6 GHz, 20 GB hard drive, 256 MB memory, and DVD-ROM drive. 

My problem:  I push the button to turn on the notebook and it comes up to a black page that says:

WE APOLIGIZE FOR THE INCONVENIENCE, BUT WINDOWS DID NOT START SUCCESSFULLY.  A RECENT HARDWARE OR SOFTWARE CHANGE MIGHT HAVE CAUSED THIS.

IF YOUR COMPUTER STOPPED RESPONDING, RESTARTED UNEXPECTEDLY, OR WAS AUTOMATICALLY SHUT DOWN TO PROTECT YOUR FILES AND FOLDERS, CHOOSE LAST KNOWN GOOD CONFIGURATION TO RETURN TO THE MOST RECENT SETTINGS THAT WORKED

IF A PREVIOUS STARUP ATTEMPT WAS INTERRUPTED DUE TO A POWER FAILURE OR BECAUSE THE POWER OR RESET BUTTON WAS PRESSED, OR IF YOU AREN'T SURE WHAT CAUSED THE PROBLEM, CHOOSE START WINDOWS NORMALLY.

     - SAFE MODE
     - SAFE MODE WITH NETWORKING
     - SAFE MODE WITH COMMAND PROMPT

     - LAST KNOWN GOOD  CONFIGURATION

     - START WINDOWS NORMALLY

(Note:I capitalized those words)  I tried both Last Known Good Configuration and Start Windows Normally but they both do't work.  They start up like the computer normally would with the Windows logo and loading screen but when that is over the screen turns blue and says:

STOP: c0000218 {Registry File Failure}
The registry cannot load the hive (file)"
/SystemRoot/System32/Config/SOFTWARE
or its log or alternate
It is corrupt, absent, or not writeable

Beginning dump of physical memory
Physical memory dump complete
Contact your system administrator or
technical support group for further assistance

I have no idea what happened.  Everything was fine when I turned it off but when I turned it on it came up to all of this stuff.