Page 1 902 Software Troubleshooting Study Guide for the CompTIA® A+ exam

How to Prepare for the Software Troubleshooting Questions on the CompTIA A+ 902 Test

General Information

While the CompTIA A+ exam content frequently changes, this outline contains the latest information we have on software troubleshooting. Continue to seek the most up-to-date guidelines as you prepare for the 902 test.

Note that all of the questions on the CompTIA A+ exam that pertain to software troubleshooting will contain a scenario to which you are asked to react.

PC Operating System Problems

Operating system issues typically have a negative overall effect on the operation of the system. This section will cover some of the most common operating system problems and how to identify and troubleshoot them. In some cases, questions will contain scenarios and ask for your response.


The only way to know how to address an operating system issue is to recognize particular symptoms. Some of the most common symptoms are covered here. Be prepared to address each of these occurrences.

  • proprietary crash screens (BSOD/pinwheel): When the system comes to an immediate halt, it will display the Blue Screen of Death (BSOD) and an error message on the screen. A BSOD that occurs during the initial boot sequence could be caused by bad hardware, drivers and/or bad applications. Apple systems will display a pinwheel or a spinning ball indicating an issue. Look for applications that try to access a resource that is not available.

  • failure to boot: There are numerous reasons a system may fail to boot, depending on the error message displayed. If the system successfully passes the Power-On Self-Test (POST), then locks up, chances are that either the hard drive or something in the operating system is corrupted. If the system does not pass the POST, suspect a hardware problem.

  • improper shutdown: If you boot a system and it enters the Windows Error Recovery screen, that often indicates the system was not shutdown correctly. You may elect to start Windows normally if this is an isolated problem. If it continues, you should launch startup repair either in the Windows Error Recovery screen, or by pressing F8 during system reboot to enter into the Advanced Boot Options menu.

  • spontaneous shutdown/restart: A spontaneous system shutdown can be caused by hardware or software problems. Poorly written programs or driver issues may cause a system lockup or system restart. Programs that make extreme demands on the processor or video (such as games) can cause the system to overheat. Thermal intermittent problems can be caused by memory, or inadequate power supplies.

  • device fails to start/detected: During the system boot sequence, there are numerous devices that are expected to start. If a device does not start correctly, check the device manager, paying particular attention to driver issues. The event viewer may also display driver-related errors.

  • missing DLL message: A dynamic link library is a piece of computer code that can be shared by numerous applications to save time when writing code. DLLs are written for a specific library and programmers require the correct library. Windows System File Check (SFC) can be used to locate and replace missing DLLs.

  • “Services” fails to start: During system boot-up, there are numerous services that are expected to start. If a service does not start correctly, check the device manager, paying particular attention to driver issues. Also, check to see if you can you start the service manually.
    If the service is associated with an application you installed, you may want to reinstall that application. Refer to the Windows Services utility for controlling services.

  • compatibility error: Applications are written for the current release of Windows. There are many older applications that will not run on the latest version of Windows. Built into the compatibility tab of an executable program, there is an option that allows the program to run in an earlier version of Windows. This is often used to run older games and applications on newer platforms.

  • slow system performance: If the system appears to be running slower than normal, the Task Manager will give a detailed listing of CPU, memory, and network utilization. Looking for applications using too much of the system resources allows you to target that application. Check for free space on the hard drive, and/or run Disk Defragmenter.

  • boots to Safe Mode: Safe mode boots the system with only drivers absolutely necessary to boot the system. If you suspect problems with drivers, or need to modify system setting that are otherwise unavailable due to booting issues, Safe Mode can help. To enter Safe Mode, repeatedly press F8 during initial boot.

  • file fails to open: File types are related to specific applications. A “.docx” file is a Microsoft Word document. If a file has had the association changed in the Default Programs, applet users may not be able to open a file.

  • missing NTLDR: If a system fails to boot and you are presented with a message that says missing NT loader (NTLDR), it indicates that critical system files are corrupted or missing. Use the startup repair disk for the appropriate version of Windows.

  • missing boot configuration data: In Windows, missing boot configuration data would prevent the system from properly booting. To address this, use the Startup Repair option in the Windows Recovery Environment to repair the boot configuration database (BCD).

  • missing operating system: A message stating missing operating system can be addressed by booting with your distribution DVD, selecting Repair your computer, and then Startup Repair.

  • missing graphical interface: A missing graphical user interface is most likely caused by either a driver issue or a corrupted system file. Boot into Safe Mode and run System File Checker (SFC) to verify all the operating system files.

  • missing GRUB/LILO: Grand Unified Bootloader (GRUB) and Linux Loader (LILO) are Linux boot loader files. Missing boot loader files can occur if you set up your system to dual boot with Linux and Windows, since windows will overwrite these files. To prevent this, always load Windows first. With a live Linux CD, you should be able restore GRUB or LILO.

  • kernel panic: A kernel panic occurs with Linux and MAC OS, whenever there is an unrecoverable system error and all system functions halt. With a kernel panic there is often an error message that should be helpful when troubleshooting the problem. A kernel panic serves basically the same function as the blue screen of death in Windows,

  • graphical interface fails to load: If the GUI fails to load, your only choices are to restore from backup or rebuild from the installation media.

  • multiple monitor misalignment/orientation: When using dual monitors to align the actions of the mouse (so that, as you exit monitor 1 to the right, you enter monitor 2 from the left), enter the screen resolution screen and drag the screens to properly orient them.


The tools listed here are used to assist in troubleshooting the problems you would encounter repairing a PC. Be certain you are familiar with all of their functions.

  • BIOS/UEFI: Many of the newer BIOS implementations have specialized hardware testing capabilities built into them. The newer UEFI BIOS even allows connecting to the Internet to download drivers and is, in itself, a fully functional operating system.

  • SFC: Any of the operating system files can become corrupted for no apparent reason. This is why System File Checker (SFC) is available to run a complete scan of the operating system files.

  • Logs: There are a number of log files created by Windows to track system performance. Most are contained in the Event Viewer, outlining security issues and other system events. To verify the boot process and events that occur during system boot, Windows maintains the “ntbtlog.txt” file. In Linux, there are numerous log files contained in the “/var/log” directory. MAC OS X maintains logs under Utilities in “”.

  • system recovery options: For operating system problems that cannot be addressed while the operating system is running, use the Windows 7 Command Prompt from the System Recovery Options. For Windows 8 and 8.1 choose Other Options > Troubleshooting > Advanced Options > Command Prompt.

  • repair disks: For additional tools necessary for startup problems, you need to create a system repair disk that provides tools and recovery options for Windows 7, 8, and 8.1. Recovery disks are created with the original distribution DVD or from Windows Backup and Restore.

  • pre-installation environments: When using a repair DVD, you are in a Windows pre-installation environment that provides minimal features, such as a GUI. This minimal environment bypassed many of the drivers that may have caused problems initially.

  • MSCONFIG: MSCONFIG provides a number of various options for booting the system, allowing you to enable/disable services and aids in configuring startup applications.

  • DEFRAG: Disks can become fragmented as files are created, deleted, and modified over time. Defrag realigns all the file fragments into contiguous files on the drive. This not only speeds up disk access, but also eliminates wear on the drive. Keep in mind that solid-state drives should never be defragmented.

  • REGSRV32: To register DLLs in Windows, use the REGSRV32 utility. The Microsoft Register Server allows you to register and unregister DLLs on the operating system.

  • REGEDIT: To edit the system registry, use the REGEDIT command.

  • Event Viewer: To see what is happening at anytime, use the Event Viewer. The Event Viewer displays information about running applications and security data. Warning messages and critical issues will be labeled there as well.

  • Safe Mode: There are a number of troubleshooting tools that are available, even before the operating system is loaded. Safe Mode allows the system to be booted with minimal drivers loaded, allowing you to address issues before the operating system loads.

  • Command Prompt: Safe Mode loads you into VGA mode and supports networking to assist in error recovery. If you’re having problems loading Safe Mode, try Safe Mode with Command Prompt, which does not load the Windows Explorer GUI.

  • uninstall/reinstall/repair: In some extreme cases, it may be easier to simply uninstall and reload the operating system. With Windows 8 and 8.1, there is an option allowing you to refresh the operating system, which allows you to maintain your personal files.