S HP Pavilion NA6740in is the latest model of desktop ??????and what is the prize of this model? plz help me......

On some systems, the light blink pattern helps diagnose the issue. See if this HP info helps at all: http://support.hp.com/us-en/product/HP-Pavilion-a1000-Desktop-PC-series/3339280/model/3339281/document/bph06788

You can use your system recovery disk to reformat and reinstall the operation system. You can use the following guide from HP support to help you and ill also link you to the drivers so u can download the latest.
http://h10025.www1.hp.com/ewfrf/wc/document?docname=bph07145&tmp_task=useCategory&lc=en&dlc=en&cc=us&lang=en&product=70996
http://h10025.www1.hp.com/ewfrf/wc/softwareCategory?os=228&lc=en&cc=us&dlc=en&sw_lang=&product=70996

Uninstall SP3. In certain cases improper installation of sp3 has caused the system to slow down.

Check to see if you're running the latest bios revision. It's on HP's support page for your model.

You need to download the drivers from the Compaq/HP WEB support/download page. Make sure you select your model laptop and the XP or Vista Windows version of the drivers you require and install them. Use this link to download the drivers: -
www.hp.com/#Support

Hi,

Are you having a Laptop or a Desktop? In case the issue is with the desktop, please check the pin ends in the CPU. In case you are speaking about the laptop, you had tried external keyboard? In that case, please try to check the Mother board pin in laptop.

Regards,
HP

you will have to but the latest model of card from what you are using at present.

You might need to update the graphics chipset for your motherboard. Go to the computer manufacturer's website and download the latest graphics driver and this will fix your problem.

Click here to go to HP

plz reinstall the driver or you can download the latest drivers from the website. plz post your findings

http://www.warezreleases.com/Drivers-For-Hp-Pavilion-Dv6602au-Notebook/full/downloads/crack/serial/Drivers-For-Hp-Pavilion-Dv6602au-Notebook.html 
All you had to do is Google "hp pavilion dv6602au"