Windows STOP: unknown hard error with the ntdll.dll file
Below are different recommendations that have been known to fix this issue.
Installation of Windows corrupt or bad
If you're getting this issue after installing Microsoft Windows make sure the CD or DVD verify the below recommendations.
Scratched or otherwise damaged disc
Ensure the disc you're using to install Windows is not scratched or otherwise damaged. In some cases a damaged disc may be able to complete the installation but errors encountered during the installation can cause this error. If your disc is damaged it's recommended that it be replaced.
Burned copy or illegal copy of Windows
If you're attempting to install Windows from a burned CD and encountering this issue it may be the cause of your issue. If the files have not been copied correctly onto the disc the installation may fail and cause this error. We suggest getting a legitimate copy of Windows.
Any of the hardware issues mentioned below may cause issues during the installation of Windows and generate this error after the installation.
If you believe any of the above were the cause of your issue after correcting the issue we suggest reinstalling Windows.
Hardware related issues
Defective EIDE/IDE cable.
Verify your computer doesn't have a defective EIDE/IDE cable by swapping your current cable with a known good one, or purchasing a new one.
Another EIDE/IDE device on the cable as hard drive
Other devices that are on the same cable as an EIDE/IDE hard drive have been known to cause this issue (this includes zip drives, CD, DVD, and burners). To help verify this is not the cause of your issue temporarily disconnect any device on the same cable as the hard drive. If this resolves your issue, the device may need updated drivers or firmware, or it may be incompatible. Try using on the other EIDE/IDE cable, may not have jumpers set properly, or may be bad.
Improper or out-of-date drivers can also cause this error. Verify that you have the latest motherboard, CD, DVD, zip drive, other disk drive drivers. A listing of links to each of the manufacturers for each of these devices can be found on our drivers listing page.
When downloading and installing the drivers verify you're using the correct drivers for the device you have installed and that you're using the drivers designed for your processor.