Click on start, Right click on computer, select manage from the pop up box & from there, choose event viewer. Have a ferret round in there for what's going on - helps if you know what time the last crash occurred as there will be many events to look through & windows times them. If you see a repetitve error report & it lines up with the crash times, you've probably (but not definitely) found it.
If that doesn't help, you can try control panel> system & maintenance>problem reports & solutions.
If you're still stuck, look here:
http://www.networkworld.com/news/200...sh.html?page=2