CompTIA+ Error Codes and Diagnostic Utilities

Boot Failure and Errors
Click on the image to zoomBoot failure is the inability to locate the operating system from the storage drives. The most common reasons for boot failures are

1. A non bootable floppy in the diskette drive.
2. CMOS is not properly configured to boot from the correct device.
3. None of the devices in the CMOS are set to bootable.
4. Hardware failure.

Going ahead we will discuss few most common Boot Failure and Errors.

Invalid Boot disk The Master Boot Record (MBR) is created when the hard disk is partitioned. The MBR has master boot code, disk signature (or end of sector marker)) and a partition table for the disk. The MBR scans the partition table for the active partition and then finds the starting sector of the active partition. It then loads a copy of the boot sector from the active partition into memory and finally transfers control to the executable code in the boot sector. This means that the MBR identifies the operating system on the disk.MBR can become corrupted due to human error, hardware problems, power fluctuations, virus attack, and other factors. An Invalid boot disk error is caused when the MBR is either corrupted or when it cannot find the partitions or the boot sector. Sometimes, it might pop an Invalid partition table or Error loading operating system or Missing operating system errors.

Invalid Boot disk (Cont...)

• Remove any floppy disks or CD-ROMs from the system & restart the system.
• Check if the Hard-disk drive is detected in the CMOS.
• Boot to the DOS prompt using a bootable floppy or CD. (Recovery Console in case of Windows XP/2000) & use the command FDISK /mbr or fixmbr.
• Reseat the Hard drive. If issue remains, replace the Hard disk drive

Inaccessible boot device
Click on the image to zoomThe error, inaccessible boot device stop error can be caused due to any of the following reasons.

• Corrupt Windows registry.
• Bad or partially connected data cables.
• Bad sectors on the hard drive.
• A boot sector virus.
• Upgrading the computer or Transferring of Hard drive from one computer to another.
• Power surge or outage.

Inaccessible boot device (Cont...)
Click on the image to zoomTroubleshooting & Solution

• Try a repair or reinstallation of the operating system.
• Recreate the MBR using FDISK / mbr.
• Delete & recreate all partitions and format the drive to delete any possible viruses.
• Reseat the data cable to the hard drive, check by swapping the Hard disk drive cable with the CD-Rom drive cable.
• Replace the Hard Disk / Data cable.

Missing NTLDR
Click on the image to zoomWhen the system is booted (turned on) it may encounter either of the following messages:NTLDR is missingPress ctrl+alt+dlt to restart system-or-Boot - can't find NTLDR-or-Windows NT could not start because the following file is missing or corrupt: <filename>This problem may be caused if one or all of these files are missing or corrupted:NTLDRNtdetect.comBoot.iniSometimes the problem is also caused due to changes or corruption in BIOS.

Missing NTLDR (Cont...)
Click on the image to zoomTroubleshooting and Solution

• Set the BIOS to default settings.
• Check that the latest version on BIOS is installed on the system. Update the BIOS if needed.
• Create a boot disk with NTLDR, Ntdetect.com, Boot.ini and Ntbootdd.sys. And copy the Ntldr, NTdetect.com and Boot.ini to the system partition. Before copying the boot.ini, modify the file to point to the correct hard disk controller and to the correct volume for the Windows installation.
• Another method is to use the recovery console on Windows 2000/XP CD. Once at the command prompt type"copy drive:\i386\ntldr c:\" (Without quotes)"copy drive:\i386\ntdetect.com c:\" (Without quotes)
• Then Edit the Boot.ini file to point to correct disk controller.
• The repair option available on the Windows CD can also be used to resolve the error.
• If none of the steps work, then reinstall the operating system.

Bad or missing command interpreter
Click on the image to zoomWhen the system is booted (turned on) it may encounter the following error messages:Bad or missing Command InterpreterEnter name of Command Interpreter (for example, C:\Windows\Command.com)This error is generally caused in Windows 95 systems when the COMMAND.COM file is missing or corrupt. The file may be corrupted due to viruses or when the system boots to DOS from Windows or vise-versa or due to damaged header. The error might also pop up when the file is deleted or renamed.

Bad or missing command interpreter (Cont...)
Click on the image to zoomSolution:Back up the current MSDOS.SYS file by typing the following commands at the prompt:c:\>cd\Windows\commandc:\msdos.sys -r -s -hren c:\msdos.sys msdos.xxxUse the SYS command from the Startup Disk to transfer the system files to the hard disk.A:\>sys c:Replace the new MSDOS.SYS file with the backup copy.c:\>cd\Windows\commandattrib c:\msdos.sys -r -s -hdel c:\msdos.sysren c:\msdos.xxx msdos.sysattrib c:\msdos.sys +r +s +h

Startup Error Messages
Click on the image to zoomStartup error messages are reported after the Operating System is located on the hard drive. During the process of actual loading of the operating system, if the system finds that a critical file is missing or corrupt or if there is a device driver conflict or a configuration conflict, an error message is generated.The following are some of the startup error messages:

1. Error in Config.sys line xxx
2. Himem.sys not loaded
3. Missing or corrupt Himem.sys
4. Device/service has failed to start

Himem.sys not loaded The file HIMEM.sys (found in the system32 folder) acts as an extended memory manager. It coordinates the use of computer's extended memory including the high memory area (HMA) so that no two applications or device drivers use the same memory at the same time. In Windows 95/98, HIMEM.sys is automatically loaded at startup. To free up more conventional memory, HIMEM.sys also allows part of DOS to be loaded into the first 64K block of extended memory known as the high memory area (HMA).On a Config.sys file HIMEM.sys is first on the device list. This is to avoid any conflict with other devices, which use EISA (Extended Industry Standard Architecture) memory. EISA is bus standard for IBM compatibles that extends the ISA bus architecture to 32 bits and allows more than one CPU to share the bus.If the Config.sys file is corrupted or if the file does not have the path to the Himem.sys file or a wrong version of Himen.sys is loaded, an error "Himem.sys not loaded" will be generated.This error was seen mostly in Windows 3.0 & in Windows 95. The error would most likely occur when the system is restarted from DOS to Windows.

Himem.sys not loaded (Cont...)
Click on the image to zoomResolution:To resolve the issue in Windows 3.0, restore the HIMEM.sys file using the EXPAND.EXE utility (available on DISK 3). Type the following command at the prompt:EXPAND A:HIMEM.sy_ C:\HIMEM.sIn case of Windows 95 or 98, doing a system generation can fix the problem. To perform a system generation, use the sys command.

• Boot from a boot diskette.
• Once at the prompt type the following command:sys c:

Running the sys command will replace the faulty HIMEM.sys file with a good copy.

Missing or corrupt Himem.sys
Click on the image to zoomWhen the computer is rebooted it displays the following (or similar) error message:"HIMEM.sys is missing."This error message will not appear when the system is started after a shutdown (Power Off). This occurs when the system is restarted. It is more likely to occur on a laptop computer than on a desktop computer.The error message "Missing Himem.sys" most commonly seen in Windows 95 & 98. This problem may occur due to two reasons, the first is when the reference to the Himem.sys file in Config.sys is to a location other than C:\Windows and the second reason is due to hardware memory issues.In case of Windows 98, if the system does not use any DOS based programs then the system will boot fine even if the Config.sys does not include the location of the Himem.sys file

Missing or corrupt Himem.sys (Cont...)
Click on the image to zoomTroubleshooting and solution:

• Shutdown and then turn on the system.
• Tap the F8 key after POST to display Windows advanced startup options screen.
• Boot the system using Safe mode with command prompt option.
• Be at the prompt and type EDIT AUTOEXEC.BAT and press Enter.
• On the text editor type SET DOS16M=2 & save and close the Autoexec.bat file.
• Edit the Config.sys file using the command EDIT Config.sys.
• Remove the NOAUTO parameter from the line DOS=HIGH, UMB, NOAUTO. (If NOAUTO is found).
• Make sure that the lineDevice=C:\Windows\Himem.sysis right after the line DOS=HIGH,UMB
• Save and close the Config.sys file and restart the system.

Missing or corrupt Himem.sys (Cont...) Another cause to the missing or corrupt Himem.sys is physical memory issues. To identify whether the issue is caused due to hardware issues or due to file corruption, perform the following steps.

• Boot the system using a known good boot disk.
• If the system boots to the prompt without any errors then the issue is not with the physical memory.
• If the error is seen even when booting from the Boot disk then the issue is with physical memory.
• Reseat the memory chip or try to boot with single memory chip (if system has more than one chip) or swap the chip to a different slot.
• If the issue remains then replace the memory chip.