My Dell vostro A840 Laptop shuts off after 5 seconds that I have turned it on, the blue light showing that is has turned. The screen is black, I don't even get the boot up screen. What will I do. thanks

Bad inverter or possibly a bad video card or M/B.

my dell vostro a840 inbulit sound is not working but i have attached my headphone is working properly how to solve this problem

Always install the chipset driver first.

I'll make sure not to advise all my clients not to buy dell its over rated over priced ****

Dear Krishna,

You can use windows 2000 Professional or Windows XP driver for Windows 2003. If you need driver let me know.I will provide you the download link.

Its stuck on finding a bootable device. your PC has a virus or HDD is gone bad (unlikely). Try putting in the OS disk n boot for it.

Enter to bios after powering and watch if it still go off. If not, go to Healt or sensors section and watch the temperature of CPU and system. The computer might turn off because of overheating.

Hold the power button for 5 seconds or more - does it turn off properly? If so, can you turn it back on afterwards?

Take out the battery and unplug the power adaptor. Let it sit for a few minutes. Now try the power adaptor alone. If this works, try shutting down and running on battery again.

well actually dell vostro a840 is not meant for entertaining purposes.It is preferably a good business laptop.that is why the sound quality is poor.

Here's a link with someone having a similar problem and solving it.
http://www.techenclave.com/laptops/dell-vostro-a840-drivers-windows-xp-135785.html
See if that helps.