When your PC is crashing with the blue screen of death at random intervals, you should make sure that you first disable the automatic reboot after the blue screen, and then write down the error message so you can Google it late
Blue screen of death
The Blue Screen of Death (also known as BSoD, "Deadscreen", Blue Screen Error, or Bluescreen), known officially as a Stop Error  or a bug check, is the error screen displayed by the Microsoft Windows family of operating systems upon encountering a critical error, of a non-recoverable nature, that causes the system to crash. The term is named after the color of the screen generated by the error. In Unix-based operating systems, a similar term is kernel panic. Stop errors are hardware, updates and driver related, causing the computer to stop responding in order to prevent damage to the hardware or data. In the later versions of Windows (Windows NT and later) the screen presents information for diagnostic purposes that was collected as the operating system performed a bug check.
Check Task Manager
The first thing that every geek is going to do when a computer is running slowly is open up Task Manager, or Process Explorer (if you've already got it installed) to see what process is taking up the most CPU or memory—that's generally the culprit. While you're in there, it's a good idea to look for other resource-wasting apps that we can kill.
Use the Reliability Monitor
This under-utilized tool is an excellent way to diagnose problems and figure out what might have caused your system problems—it will show you a full history of system crashes, application problems, and even Windows Updates, so you can track down what changed on your system right before your system started running slow. Just type in reliability into the Start Menu search box, and you'll be able to see everything, and even drill down into specific errors to see...