Alpesh Nakar Blogs on SharePoint, Microsoft and that’s IT

This registry hack will ensure that Windows Vista does not wait for a service to stop before prompting you to forcefully stop it. Just decrease the time, Windows Vista will shut down quicker. This can be achieved via hack of your registry.
*Registry hacks are dangerous. Be warned, take a backup, before performing this hack. I will not be liable for any loss.*

1) Access your registry editor: Open up the Start Menu, and type regedit in the Search bar. When working with the registry editor, it is always a good idea to make some sort of a backup in case you make a mistake. You can access it by going to File > Export.

2) Navigate to [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control]

3) Edit the WaitToKillServiceTimeout=20000 - By default, the setting is at 20000 milliseconds (20 seconds.) The default setting are the safest settings for your computer. By lowering this amount, there is some degree of risk involved. I would suggest you lower it in 5 second increments to see what works for you. It is generally recommended that you do not lower it more than 3-5 seconds. Doing so will cause your computer to shut down improperly or lose data.