how do i find out whats causing my computer to turn off

[srchop16]

my computer randomly shuts off, i'll be browsing the web then out of the blue the screen will flash and the computer reboots, every now and then it will flash a blue screen for a second, then reboot.

what can i do to test what is causing it?

 

[KSoD]

Start>Right click on My Computer>Properties>Advanced tab>Startup and Recovery>Settings.

Uncheck the box for auto restart on system failure.

This will allow you to see the BSOD (Blue Screens of death) and get the Stop error code which will looks like this:

0X000000ZZ where ZZ is a alpha numeric combination. Also a few lines down you will see a line in all CAPS.

Get us that info for us to help you further.