I found this on MS knowledge base :
SYMPTOMS
When you attempt to run ScanDisk in Windows Millennium Edition (Me), you may receive the following error message:
ScanDisk cannot check this drive now because the disk is not properly formatted, or a program such as a disk utility has locked it. Format the disk or wait for the utility to finish, and then restart ScanDisk.
CAUSE
This issue occurs if the Norton Speed Disk utility is running. When the Speed Disk utility is running, it blocks the use of ScanDisk. Speed Disk is installed when you install Norton SystemWorks 2000.
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Maybe you should uninstall System works then run scandisk and reinstall it to get around this problem or uninstall the speed disk part if that is possible with the add/remove and modify bit :doggie: