4.1.1. Troubleshoot common Windows OS issues. (Obj. 3.1)

💡 First Principle: Isolate the issue by differentiating between system-wide failures (OS), application-specific failures (app), and external factors (connectivity).

When a Windows computer misbehaves, the symptoms can range from a minor annoyance to a complete system failure. A technician's job is to interpret these symptoms and follow a logical path to the root cause.

• Blue Screen of Death (BSOD): This is a Windows "stop error," a critical failure from which the OS cannot recover. The blue screen itself contains vital clues, including a stop code (e.g., IRQL_NOT_LESS_OR_EQUAL) and often the name of the faulting driver file (e.g., nvlddmkm.sys). Your first step is to research this stop code. BSODs are most commonly caused by faulty hardware (especially RAM), corrupt drivers, or low-level system file corruption.
• "Operating System Not Found" / Boot Failures: When the computer starts, you may see an error like this. This points to a problem in the boot process. Your theory should be:
  1. Is the boot order in the BIOS/UEFI correct? Maybe the PC is trying to boot from a non-bootable USB drive.
  2. Is the boot drive physically connected and detected by the BIOS/UEFI?
  3. Is the boot sector (MBR or GPT) corrupt? Tools like bootrec /fixmbr and bootrec /rebuildbcd from the Windows Recovery Environment can fix this.
  4. Is the drive itself failing?
• Applications Crashing / Freezing: If a single application is crashing but the rest of the OS is fine, the problem is likely with that application. Check Event Viewer for application error logs. The solution often involves updating the application, reinstalling it, or checking for conflicts with other software or drivers.
• Slow System Performance: This is a common complaint with a wide range of causes. Use Task Manager to see what's consuming resources (CPU, RAM, Disk). It could be a runaway process, too many startup programs, not enough RAM, a failing hard drive (indicated by 100% disk utilization), or a malware infection.

Technician's Diagnostic Path: Scenario: A user reports that their PC has started crashing to a Blue Screen of Death (BSOD) several times a day. It seems to happen randomly. You are able to get it to boot.

1. Identify the Problem & Gather Clues: The problem is intermittent BSODs. Ask the user: "When did this start? Did you install any new hardware or software recently?" The user mentions they updated their graphics card driver two days ago. You note the stop code from the last crash: SYSTEM_SERVICE_EXCEPTION.
2. Establish a Theory: The timing strongly suggests the new graphics driver is the cause. The driver may be buggy or incompatible, causing a conflict at the kernel level. A secondary theory is failing hardware, like RAM.
3. Test the Theory (Driver First):
   • Boot Windows into Safe Mode. If the system is stable in Safe Mode (which uses a generic video driver), this strengthens the theory that the graphics driver is the problem.
   • In normal mode, open Device Manager. Find the display adapter, right-click it, go to Properties -> Driver tab.
   • Click "Roll Back Driver". This will uninstall the new driver and revert to the previously installed, stable one.
4. Verify Functionality: After rolling back the driver and rebooting, use the computer normally. If the BSODs do not recur for a significant period (a day or two), you have likely found the cause.
5. Establish a Plan of Action: The rollback is the immediate fix. The long-term plan is to visit the graphics card manufacturer's website and look for a different, stable version of the driver—perhaps a slightly older one or a newer beta version that specifically addresses the bug.
6. Alternative Test (if driver rollback fails): If the BSODs continue, your next theory is faulty RAM. Run the built-in Windows Memory Diagnostic tool or a more thorough tool like MemTest86 overnight to test the memory modules for errors.

Reflection Question: When a Windows PC experiences a Blue Screen of Death (BSOD), what is the most important piece of information to note from the blue screen itself, and why?