Vista - Processor hits 90-100% and shuts down

I keep having this problem where using DVD Shrink or Windows Movie Maker will max out my processor between 90 and 100%. After a minute or two of converting a DVD or publishing a movie, my computer will just shut down. I've tried closing pretty much every other application I can and the problem still persists. Here are my computer specs:

Windows Vista Ultimate 64-bit
5.2 Windows Experience Index
Intel Core 2 CPU - 6600@2.40Ghz
2046 MB ram
700 Watt power supply

Any thoughts?

Thanks

I think its ur CPU Overheating.
What are the temps like when it maxes out ur CPU to (90-100)% ?
The temps may be reaching the threshold limit causing CPU to shutdown to prevent damage.
Make sure the Heatsink is seated properly.
Also,remove dust(if any) between the fins of the CPU FAN.

I cleaned the dust off of the fans and it looks like the heatsink is situated properly.

I installed SpeedFan to check the temps and when I try to publish a movie, the temps are around 60-70 C. The processors are hovering around 90-100% still so I canceled the movie publishing before it shutdown.

Normally, it looks like the temps are around 40-50 C.

60-70C shudnt cause a shutdown but as u said u cancelled the movie so i guess it goes above 70 and then shuts down.
You said normally temps were 40-50C.is that at Idle or at Load(i.e with a program like DVD Shrink).
I still think that the heatsink isnt making proper contact with the CPU.

Since u have Core 2 Duo ,try Coretempand post the temps here .

Are you overclocking your CPU ?

hope this helps.

I don't overclock. This morning, I removed the heatsink and reinstalled it. It's is fitted properly as far as I can tell. However, now the problem is even worse. When I turn on the computer, it keeps shutting down before Windows even loads. I am able to load Windows in safe mode though.

In safe mode, I can open SpeedFan (sorry but the program you suggested kept giving me driver errors). The CPU temp now is 65 C, so I'm guessing it is something I did with the heatsink, but I don't know. The CPI fan is running at 1700 RPM.

Please help.

Okay, I removed the heatsink again and cleaned off the thermal grease. It wasn't an even spread so maybe that was the problem. I bought some more and applied a new layer. Then I reset the heatsink. It took some manuevering but I'm almost certain it is now situated properly. It doesn't budge at all, when before it would wiggle a little.

With that done, I can load Windows again.

Right now, I have Internet Explorer, SpeedFan, Windows Sidebar, and dual monitors running. SpeedFan says the temp is around 45 C. I am going to try to publish a movie with Windows Movie Maker, and will let you know what happens.

EDIT - Okay, last night when i having the shutdown problems, I couldn't publish a movie in Windows Movie Maker larger than 25 MB. I just made one that was 75 MB and it didn't shutdown. SpeedFan had the temp at 59 C and the CPU fan was running at about 1500 RPM. The processor was still running between 90 and 100%, but it didn't shutdown. As I'm typing this post, the temp has dropped back to 45 C.

Asky, it looks like you were right about the heatsink. Thank you very much!!!! However, I still don't understand why the processor is running at 90-100%. When I was having the DVD Shrink shutdown problem, I figured it was due to the program's incompatibility with Vista Ultimate 64-bit. That wouldn't apply to Windows Movie Maker. Any thoughts on that, or other suggestions to keep the temp down?

Thanks again. You don't know how much I appreciate your help!

No Problem mate , Glad i could help
Hmm...buy a good CPU Cooler if you can ,i think the conditions in your area are hot somewhat ( same here).
Buy a coooler like the Tuniq Tower 120 or Thermalright Ultra 120 (make sure it fits in your Case first).That would help bring down the temps.