Halp

Okay, for a while now, I've been faced with the "NTLDR is missing" error message. I've decided to try and do a repair of Windows. When I try, my fan speeds up, and my PC shuts down. Tried again, same results. My PC also shuts down when left on for a few minutes. Obviously, not eunning any programs, due to the "NTLDR is missing"

 

It sounds like a heat problem.

Remove the case cover/LH side panel and check for/remove dust on all venting openings for the case and the power supply.

Check the CPU Heatsink/fan assembly for dust buildup.

Use the methods outlined in this article for dust removal. (Near the end of the article)

If there's not much dust and heat isn't the issue, it could also be ;
Power Supply
RAM
Motherboard
CPU
a failing peripheral component (Hard disk, NIC, etc)

The quickest method for determining the culprit is swapping these items out. However, not everyone has spare/duplicate components laying around.

Check this article on troubleshooting Boot/POST problems;
http://www.d-a-l.com/articles/library/34.html

NTLDR Missing;
http://support.microsoft.com/kb/555304/en-us
http://www.computerhope.com/issues/ch000465.htm

 

At what point does your computer do this in the repair install?