The system hangs after the POST

You turned the system on, it went through the POST process, but then it stops, does not continue to boot, and you see no error messages. This could be caused by several things. Is the hard drive that you are trying to boot from, partitioned, formatted, and have an active partition? Use a boot floppy to boot to a DOS prompt, then use the FDISK command to check the partition information on the drive(s).

“Missing Operating System”

You turned the system on, it went through the POST process, but then it stops with an error message “Missing Operating System”. This means that the drive it is trying to boot from has no operating system installed on it. To make the drive bootable, boot with a floppy disk to a DOS prompt, then type sys C:. This will copy COMMAND.COM to the C: drive to make it bootable. This method also helps if COMMAND.COM has been erased or corrupted.

Another possibility is that the operating system is installed, but the master boot record is damaged or has been altered by a virus. Boot with a Windows startup disk, then run fdisk /mbr. It will restore a clean master boot record.
Caution: If your system is a dual-boot setup using Linux’ LILO boot loader, or NT’s boot menu, or a third-party multi-boot utility such as Boot Magic or System Commander, or if you have to use some type of drive overlay software such as EZ-BIOS to compensate for the BIOS’ inability to recognize large hard drives, this command will erase this custom setup and you have to recreate it!

“Invalid System Disk” or “Boot Disk Not Found” or “Insert System Disk”

You turn on the PC, it goes through the POST, then you get the error “Invalid Disk. Replace the disk and and then hit any key.” First, check your floppy drive. Is there a floppy disk in the drive? Remove it and hit a key on your keyboard and see if it boots now. If the floppy drive is empty and you still get this error, it means that the drive you’re trying to boot from, does not have system files on it.

Hard drive is not detected during POST

Check your hard drive first and make sure that the hard drive is properly connected. Is the power cable plugged securely into the correct plug? Is the data/ribbon cable connected correctly? Make sure that the red line on the ribbon cable is in line with the Pin 1 markings on the IDE controller on the hard drive and on the hard drive connector. Make sure that the hard drive is jumpered correctly. For more information on configuring IDE devices, read our articles on Installing IDE drives and Building your own PC. If you have SCSI drives, make sure they are terminated properly and that you assigned the ID numbers correctly and uniquely. For more information on configuring SCSI devices, read our article on SCSI devices.

Also, check the BIOS and see how it is set up to deal with hard drives. Did you enter the settings for the drive manually? Try setting the BIOS to auto-detect and let it find and identify the drive(s) automatically.

Windows does not load automatically

Your PC powers up correctly, it passes the POST, all drives are detected correctly, but Windows does not load. Instead you only see a DOS prompt. The reason for this could be that the Windows directory cannot be found or accessed. Boot to a DOS prompt with a Windows startup disk. When you’re at a DOS prompt, make sure you’re at the C:\ prompt. Then type attrib -s -h -r msdos.sys and hit Enter to remove the system, hidden, and read-only attributes for this file. Now type edit msdos.sys and hit Enter. In the resulting window, look for the section titled [Paths] and see if it has the lines WinDir=C:\Windows and WinBootDir=C:\Windows and make sure that the path after the ‘=’ sign corresponds with wherever Windows is installed. If those lines are not present for some twisted reason, add them manually as follows:

[Paths] WinDir=C:\Windows

After making the necessary corrections, save the file and exit the editor. Now reset the correct attributes for the file by typing attrib +s +h +r msdos.sys and hit Enter. Now reboot and see if it now boots correctly into Windows.

Page 1: Computer boot problems
Page 2: Diagnosis of boot problems
Page 3: This page
Page 4: POST running OK but Windows not starting

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