Dealing with DLL errors can be frustrating, especially when the error message suggests that a DLL file ‘is not designed to run on Windows’. This error can prevent software from running and may pop up after updates or software installations. Here are the top 9 fixes to help you resolve this issue:

1. Reboot Your Computer: Start simple. Before diving into complex troubleshooting, restart your computer. This can often resolve temporary glitches causing the error.

2. Run SFC and DISM: System File Checker (SFC) and Deployment Image Servicing and Management (DISM) are built-in Windows tools that can fix corrupted system files. Run SFC by opening Command Prompt as administrator and typing `sfc /scannow`. Follow it with DISM by typing `DISM /Online /Cleanup-Image /RestoreHealth`.

3. Check for Windows Updates: Keeping your system up-to-date is critical. Go to Settings > Update & Security > Windows Update and check for any pending updates.

4. Reinstall the Troublesome Application: If a particular application is causing the DLL error, try uninstalling and then reinstalling it to ensure all its components are correctly installed.

5. Download the DLL File from a Trusted Source: If a specific DLL is missing, you may be tempted to download it from the internet. This can be risky; if you must do so, ensure it’s from a reliable source, preferably the original software vendor.

6. Restore Missing DLL from Recycle Bin: In case you’ve accidentally deleted the DLL file, check your Recycle Bin to see if you can restore it.

7. Run a Virus Scan: Malware can cause DLL errors. Use your antivirus software to run a comprehensive scan of your computer.

8. Use System Restore: If you suspect that recent changes caused the error, use System Restore to take your system back to an earlier point in time when everything worked correctly.

9. Perform a Clean Installation of Windows: As a last resort, if nothing else works, back up your important files and perform a clean installation of Windows.

These fixes cover a range of easy-to-perform solutions and more drastic measures like reinstalling Windows. One of these should hopefully resolve the ‘DLL is not designed to run on Windows’ error.