Vista - Fatal error c000021a

Recently my notebook has been shutting down unexpectedly without warning. It
simply turns off instantaneously . When turning the
system on and booting for a while, I get a blue screen with a fatal error
coded c000021a and a crash dump is done. The sytem then restarts and
sometimes boots to the same blue screen 2-3-4 times before entering vista.
Could this be a software problem or does it sound like hardware for sure??

 

F8 on startup, select last know good configuration. See MS article on this:

http://support.microsoft.com/default.aspx?scid=kb;en-us;156669

This error is due to mismatched system files, faulty SP install, faulty restore, or imcompatible third party program installed. Unless you did one of the other three, I'd go with the SP install and the instructions I gave in the beginning should solve it.:wave:wave:wave

 

As far as the notebook turning off completely - this usually indicates a heat problem. Any computer that shuts down will do so when the temperature reaches a certain point in order to protect the CPU.
You may want to open the notebook up and clean it out. One or more of the fans might not be working.