I seriously suggest that you use PC Restore (page I04 of the 6400 Owner's Manual).

When your computer was shipped from the factory there was a hidden partition on the hard drive with an image of the hard drive at that time. The purpose of the image is to allow you to return the computer to the state it was in when it left the factory if you ever should have unresolvable problems. I would use that image now, but if you have ever reformatted the entire hard drive the image is gone and there is no way to get it back. PC Restore is an image of your original operating system, drivers, applications and configuration settings.

To use PC Restore you first save all of your data files to removable media or to an external hard drive, then restart and tap Ctrl + F11 and it should take you to the "PC Restore" menu. Anything that doesn't work afterward either wasn't working when the computer was shipped or is the result of hardware malfunction.

If you cannot use PC Restore then try posting your question on the Software & Operating System Board for a better chance at getting an answer specific to your Windows problems.

Thank you so much, it worked. but i wish there was another way, because i have to install all my softwares again.

Thanks again :)