Blue screens in Windows operating systems represent a variety of problems that stop the computer from working properly and require a restart. Often called stop errors, black screens, bug checks and even "Blue Screens of Death," these errors can occur for a variety of reasons. While they were more frequent in Windows XP than newer operating systems, they're still around in Windows 7.
Malfunctioning Hard Disk and Memory
Various errors with your computer's hard disk or memory often cause blue screen errors. If either of these components are defective, improperly installed or incompatible with the rest of the system or another component, it may cause a stop error. The "DATA_BUS_ERROR" blue screen indicates a defect in your computer's memory, hard drive or motherboard. Similarly, "KERNEL_STACK_INPAGE_ERROR" often is encountered by defective or improperly configured memory or hard drives, though it also can be caused by improper cable configuration, data corruption or a virus.
If you've overclocked your computer by increasing the performance of the hardware components, such as your CPU, over their factory settings, the overworking can cause various blue screen errors. Examples include the "MACHINE_CHECK_EXCEPTION" and "UNEXPECTED_KERNEL_MODE_TRAP" screens. Both indicate problems caused by defective hardware such as a malfunctioning fan or power supply or overclocking the CPU.
Drivers are the software your computer uses to allow the various hardware components to interact with each other and the programs on your computer. Every piece of computer hardware requires a device driver, which leaves plenty of room for something to go wrong. A faulty or missing driver means that the device it belongs to, such as your hard drive, can't communicate with the rest of your computer. For example, a common error with faulty drivers displays a message reading "Bugcode 0xA - IRQL_NOT_LESS_OR_EQUAL," which basically means the driver was trying to access a specific memory space that doesn't exist on your computer. This represents an error in the actual computer coding written into the driver.
Microsoft admits that these error screens stem from both hardware and software problems, making them difficult to diagnose. Things such as software incompatibility can cause the "PAGE_FAULT_IN_NONPAGED_AREA" error, especially if the problem begins soon after installing or updating software. CNET's Elinor Mills reported that a February 2010 Microsoft Windows 7 security update gave some users with the 32-bit version of the software a blue screen error that required a Windows 7 installation CD to fix.