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Manually Fixing Rundll

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Although fixing Rundll errors with automated tools such as SlimCleaner Plus is the recommended route, we have compiled a bunch of step-by-step instructions to fixing most Rundll issues. WARNING: this guide is intended to be followed precisely.

The very first thing you should do is to REBOOT YOUR COMPUTER!!!

Many Windows errors, including Rundll32, can be resolved with a simple reboot of the system. Perhaps something silly went wrong and Windows just needs a fresh start. Hopefully, the problem you are experiencing will only require a reboot of your computer, but if not then take the following steps to continue your investigation...

Are you attempting to run a particular application that causes the error...
If you can not do anything without receiving errors then proceed to the next section; however, if you only receive the Rundll32 error when running a particular application, continue reading.
When Windows is giving you the Rundll32 error, are you trying to run a particular application that continues to give the error every single time? If there is a particular application that is causing the error, you may just need to uninstall the application, reboot the computer and re-install it. Rundll32 errors are often caused when a program installs itself incorrectly or if the file is corrupted or if it is infected by malware.
If you do re-install the program and it still is causing the errors, then you should continue with the steps below.

Is your computer clean of infections and properly protected...
Occasionally, malware will attempt to masquerade as Rundll32. I strongly recommend you run an scan on your computer to see if there are any threats on your computer that are potentially corrupting Rundll32.exe. Run several different scans from different anti-malware programs to ensure that you are clean but don't forget to remove any extra on-access scanners that you downloaded. Running more than one on-access scanners can cause your computer to slow down significantly. Once you have verified that your computer is clean, continue to the next step.

Next, let's verify the location of Rundll32.exe...
Remember, it should be in C:\Windows\System32

  1. Click Start
  2. Click My Computer/Computer
  3. Double-click the C:\ drive
  4. Double-click the Windows folder
  5. Double-click the System32 folder
  6. Browse the contents of the System32 folder for Rundll32.exe

This folder is organized alphabetically by folders and then files. Rundll32.exe is an executable file, not a folder.
Since there are many files in this folder, press the R key on your keyboard until you locate the Rundll32.exe file.

If you found Rundll32.exe in C:\Windows\System32 then you should continue on to the next section. If you did not find Rundll32.exe in C:\Windows\System32 then you should take the following steps...
Note: If you cannot find the “dllcache” or the “ServicePackFiles” folders, simply ignore these steps as they do not apply to you.


  • Look for Rundll32.exe in C:\Windows\System32\dllcache
  • Look for Rundll32.exe in C:\Windows\ServicePackFiles\i386

If you were able to find a copy of Rundll32.exe in one of the above locations, you can use that copy of the file to replace the corrupt or non-existing Rundll32.exe in C:\Windows\System32 by taking the following steps...

  1. Right-click the Rundll32.exe file you found and select Copy from the menu
  2. Navigate to C:\Windows\System32
  3. Right-click on a blank area of this window and select Paste from the menu
  4. Reboot your computer

If you are still experiencing Rundll32.exe errors, continue reading and follow the steps.

Repair installation of Windows...
The Rundll32 file can be replaced by running a repair installation of Windows. The repair installation will fix a corrupt or missing Rundll32 file. To attempt this fix, you will need the Windows installation/recovery CD/DVD that came with your computer. If you did not receive one or you have lost it, you may want to contact the manufacturer for one, purchase one on the Internet or else move on to the next section. A repair installation of Windows is different for each Windows operating system. In order to perform the repair installation correctly, follow the steps designated for your operating system...

Windows XP:

  1. Insert the Windows XP CD/DVD into the disc drive.
  2. Boot the computer using the Windows XP CD/DVD.
  3. You may need to change the boot order in the system BIOS! To access the BIOS setup, you must press a particular key when your computer is booting up. The key differs per manufacturer but it is usually either Esc, F1-F12, Delete.
  4. When you see the “Welcome To Setup” screen, press ENTER
  5. Accept the License Agreement
  6. Windows will now search for existing installations of Windows.
  7. Select the XP installation you want to repair from the list.
  8. Press the R key to start the repair.
  9. The setup will copy the necessary files to the hard disk and reboot automatically.
  10. Do not press any keys during the setup. Windows may reboot several times.
  11. Follow the instructions provided by Windows to complete the initial setup but choose to “Activate Windows Later” when prompted.
  12. Once the setup is complete, it is critical that you download and install all updates from Microsoft.

Windows Vista:


  1. Insert the Windows Vista CD/DVD into the disc drive.
  2. Press any key to boot from CD or DVD...
  3. The Setup will load and prompt you for the language, time and input method you wish to proceed in. Enter your preferences from the options provided and click Next once you are finished. Do not click Install Now!
  4. Click Repair your computer - Windows will search for installations of Windows.
  5. Select the Windows Vista installation you would like to repair.
  6. Click on the Load Drivers button
  7. Click the Next button
  8. Select the Startup Repair tool from the list that appears. - If the Startup Repair initiates automatically, ignore this step. -The Startup Repair process will take some time to finish. Your computer may reboot several times. - If you are prompted to restore the computer using System Restore, click Cancel.
  9. Once finished, you will have the option to view the details of the repair. Simply click Finish to continue.
  10. Windows Vista may run through the initial setup phase. Simply follow the instructions but choose to “Activate Windows Later” when prompted.
  11. Once the setup is complete, it is critical that you download all updates from Microsoft.

Windows 7:

  1. Log on to Windows 7 as an administrator.
  2. Disable any 3rd party firewall, antivirus or any other security software.
  3. Insert the Windows 7 CD/DVD into the disc drive.
  4. If the AutoPlay menu pops up, select the option “Run setup.exe” - If AutoPlay does not appear, double-click Computer on the desktop, double-click on the disc drive icon, and run the setup.exe file within.
  5. If prompted by the User Account Control, select Yes
  6. Click on the Install Now button.
  7. Click the Go online to get the latest updates for installation option - Windows will now check for any available installation updates.
  8. Accept the license agreement from Microsoft.
  9. Click the Upgrade option - Windows will now begin the repair process. - The computer will reboot several times during installation.
  10. Once the setup is finished, you will be asked for your Windows 7 product key.
  11. Uncheck the box next to Automatically activate Windows when I'm online
  12. Click the Use recommended settings option.
  13. Windows will guide you through the rest of the initial setup.
  14. Once Windows has loaded, it is critical that you download and install all updates from Microsoft.
  15. Do not forget to re-enable your anti-virus and firewall. - This concludes the tutorials for attempting a repair installation of Windows to correct the Rundll32.exe error. If this process did not work then you MOST LIKELY have a hardware failure that is likely to be the hard drive. However, there are still a few steps that can be taken to ensure that a hardware failure is the true cause of the errors.

Borrow your buddy's Run32dll...

As a last resort, you can attempt to copy the Run32dll.exe file from a known, working computer and paste it into the C:\Windows\System32 directory. To attempt to perform this fix, I recommend you use a USB flash drive to transport the Rundll32 file from the working computer to the problem computer.

WARNING!!! - Make sure that you only attempt to copy and replace your Rundll32.exe file with a Rundll32.exe of the same operating system. Ex: Do not use a Windows XP Rundll32.exe to replace a Windows Vista or 7 Rundll file.
Attempting to use the wrong file could cause unexpected results. Proceed with caution...

On the working computer...


  1. Insert the USB flash drive
  2. Navigate to C:\Windows\System32
  3. Locate the Rundll32.exe file
  4. Right-click the file and select Copy from the menu
  5. Open the USB flash drive from My Computer/Computer
  6. Now, Paste the file into the USB flash drive
  7. Safely eject the flash drive

Now, we have a copy of a working Rundll32.exe on a USB flash drive...
On the problem computer...


  1. Insert the USB flash drive
  2. Open the USB flash drive from My Computer/Computer
  3. Locate the Rundll32.exe file on the USB flash drive
  4. Right-click the file and select Copy from the menu
  5. Navigate to C:\Windows\System32
  6. Now, Paste the file into the System32 folder
  7. Safely eject the flash drive
  8. Reboot the computer

After all the steps we have taken, you should no longer be experiencing any errors. If you are still experiencing errors then there is most certainly a hardware failure that is likely to be the hard drive.
You should now know how to troubleshoot a Rundll32.exe error. If you ever experience this issue again, you can always refer back to this guide to walk you through the steps again. We've always got your answers!