I was having this problem recently and I tried my best to resolve it by suggested online options on the internet. I also checked Microsoft website but their method did not help at all. Then I finally got over this problem. Here's how:
1) Right click on the battery image on the bottom right hand corner of your laptop or pc.
2) Click on the more power options.
3) Depending on your choice of battery meter, you may have either Balanced, Powersaver or High Performance plans selected.
4) Click on the change plan settings link under each one of the plans.
5) This will bring up the edit plan settings window.
6) Now Click on the restore default settings for this plan link. Click "yes" in the next alert popup.
7) Close the power options window.
The above trick solved the Windows Vista shut down problem on my laptop. There may be many other tricks.
If you found the above trick useful then please leave a comment. Thank you.
