Start in safe mode

When it's starting up, keep tapping F8 until the Safe Mode options show up on the screen and select Safe Mode.

sounds like a bad hard drive
check with this
http://crystalmark.info/redirect.php?product=CrystalDiskInfo

If you can start it up on safe mode go and back up the files that you needed because formatting the HD will be needed and reinstalling the operating system. You can also download malwarebytes first and run it during safe mode. once it is finish restart it in normal mode if it does not work perform the 1st step above.

If you mean safe mode, as soon as you turn on the computer start pressing the F8 button about once a second. That should bring you to the safe mode option.

With this kind of problem, you must put in the Windows software disk and boot. Then select repair Windows from the list. This option will attempt to correct the problem.
If you do not have the disc, boot into the repair / diagnostic mode from the boot screen. See if there is an option to create boot disks.

Scan the Computer using any latest updated anti virus program for any potential threat.

If the computer is not infected by any virus or trojan then you may also try performing System restore to the time when the Computer worked normally.

If the Computer keeps shutting down randomly after turning ON then the Power Supply Unit in the Notebook requires service.

Here's Toshiba's site for drivers:

http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/home.jsp#

You need to know what the last part of your model is:

A70-????

Let me know if you need any more help.

http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/modelContent.jsp?ct=DL&os=&category=&moid=835412&rpn=PSA70U&modelFilter=A70-S249&selCategory=3&selFamily=1073768663&selModel=835412|PSA70U


here u can find driver for ur odem...

toshibas site has downloads for a70

http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/home.jsp?nav=Product%20Support

you´ll need to know the submodel to get the correct drivers for your system

It sounds as though Windows Vista was either a pirated copy, or the installation of it has corrupted the original XP install in some way. It also sounds as though your computer either has missing drivers (sound problem) or serious hardware issues. What does the message that comes up when you start your computer say?