Vista - Unexpected shutdown

From time to time my system (Vista64) shuts down - when IDLE - for no reason.
WIndows restarts and says: Windows recovered for an unexpected shutdown... error report send.

How to debug? Note that the system is idle; only background processes are running.

What I've done sofar:
- Ran extended memory test: no problem
- Disabled power saving settings (as I suspected a problem going into hibernate/sleep). No effect.
- Disabled all "user based processes" as Picasa, Google indexing, CPU-temp watcher etc..
- Removed all USB sticks (no readyboost anymore)

No help. I leave the system idle and 10minutes to 2hours later; bang; shutdown
Note also that the system never chrashed when I'm actually working.

So, not a severe issue but I feel intellectually challenged to get the thing under control.
Any idea's on how to proceed further?
Alfred

Try looking in schedule task. A task may be running when the computer is idle for a time limit.

Try looking in your error logs by;

Left Click on Start Menu.
Right click on Computer and choose manage.
Click on the event viewer.
You now have loads of options to try and pin down what is happening.
Expand the error tab.
Look for things in the last 24 hours.

solution was not working...

The most likely cause for this sort of errors is video or storage drivers.

Let us have a look at the memory dumps that were generated from the crashes.
To do this, navigate to C:\Windows\Minidump, zip up the files there, and upload the .zip file in your next post.

If it won't let you zip them, copy them to your desktop and then zip them up.

Could you help me please? Attached is the zip file of my mini dump and other files from my error. It has to do something with my hard disk don't know what it is!

danieldebest - please start your own topic and I'll offer my advice there.

Ok I opened a new thread.