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 more details.
Use the Advanced Tools in Windows 7
Windows 7 has quite a number of useful tools to troubleshoot performance problems, but they're buried in Control Panel where you might not think to look. Just head to Performance Information and Tools –> Advanced tools and you'll see a list of performance issues along with suggested fixes for the problems.
Trim Down Startup Apps to Speed Up Boot Times
This applies both when your PC takes forever to boot and when you've got a glut of applications running away in your system tray that you don't need; it's time to trim down your startup applications. You can use the built-in MS Config utility or any number of tweaking applications, but you might want to take a look at Soluto, which not only helps you disable startup applications, but it shows you exactly which ones are affecting your boot times the most. Write to us about any issue related to Microsoft Windows XP, Vista and 7. We would also like to hear about issues with the older Windows Operating Systems like Windows 98, Millennium Edition (ME), Windows 2000 etc.
As a Tech Support Engineer/Analyst, your customers will expect you to know “everything about everything” – but this is impossible. So, learn how to quickly search for information – online and offline. There’s nothing more important than technical knowledge – always keep yourself well informed about the latest developments. Acquire technical certifications whenever possible.
How to Repair the Windows Installation in your computer?
Boot from the Windows XP installation CD
Choose press enter to set up Windows XP now
Press F8 to skip through the End User License Agreement (EULA) Now press R to begin a repair installation
(Remember you can also search for a solution on the internet with only the error number or the file name mentioned in the error message. These are just a list of general things you can do to fix a blue screen error, also known as “BSOD” or “Blue Screen of...