Microsoft

Tech Tip: Troubleshoot ScanDisk problems

Windows 95 OEM Service Release 2 and Windows 98 systems may prompt you to run ScanDisk at startup after displaying the messages: "Windows was not shut down properly" or "One or more of your disk drives may have developed bad sectors."

These versions of Windows include a feature that checks the Clean Shutdown and Hard Disk Error bits in the system's Virtual File Allocation Table (VFAT). The Clean Shutdown bit is cleared when Windows shuts down completely and properly, and the Hard Disk Error bits are cleared when ScanDisk completes a surface scan—whether errors are fixed or not.

However, if Scandisk.exe is corrupt or the .exe file isn't found, the error message and ScanDisk failure may occur each time Windows boots. If ScanDisk fails to start and you see the messages "Scandisk could not be found" or "There was an error running Scandisk.exe," try replacing Scandisk.exe from the original installation media and then reboot.

When this option isn't possible and you need to troubleshoot an affected system, try adding the following line to the [Options] section of the Msdos.sys file:

AUTOSCAN=0

This will turn off the feature that checks the Clean Shutdown and Hard Disk Error bits in the VFAT. It forces ScanDisk to not start when Windows is started.

If you change the AUTOSCAN value to equal 2, it forces ScanDisk to start on Windows startup, but no warning message occurs—ScanDisk just starts.

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