Laptop troubleshooting: Confused?Keyboard or Motherboard issue. Need help

Confused?Keyboard or Motherboard issue. Need help

Hi Guys,

I own a DELL studio laptop(warranty is expired recently). I am unable to boot the system. After wasting precious time and money with DELL TECH SUPPORT (they are real monsters on the earth), I am finally derived following points about laptop.

1) If I boot my system : after the DELL logo, a blank screen appears with a white cursor on top left corner after sometime system automatically gets shutdown with some beeps.
2) I could not enter into setup/bios as my key board is not responding.
3) If I connect an external keyboard and press NumsLock key and caps lock key, my laptop keyboard responds to those key presses.
4) When the DELL support person had disconnected the Keyboard connection in the laptop, the system has booted properly and it was showing WINDOWS VISTA login screen. But unfortunately I did not have ab external keyboard with me at that time to login to windows.

Now can I assume that the problem is with the laptop KEYBOARD and if I replace it, I am able to work with laptop?
OR
do I need to replace the mother board also as the DELL TECH support person reading the instructions from their so called WORST KNOWELDGE BASE.


Thanks a ton in advance for the responses..pls help me out.