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Popup with what to open DLL file?

Mark and Debra Littleton 0 Reputation points
2025-11-09T12:57:26.9266667+00:00

Periodically, a popup appears and says What software do you want to open dll file. I selected Notepad. A popup with a ton of different tabs appears with different files?? and Notepad is showing jibberish. Some files look like they're photos. Others I'm not sure what they are. How can I fix this issue so I no longer get this popup. I'm fearful that it could be a virus...

Windows for home | Other | Security and privacy
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  1. Deleted

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  2. Lucus-V 7,395 Reputation points Microsoft External Staff Moderator
    2025-11-10T09:11:22.9333333+00:00

    Hi Mark and Debra Littleton,
    Welcome to Microsoft Q&A forum. I'm happy to help.

    The DLL filetype is not meant to be opened manually, especially by text editor application like Notepad.

    If you did that intentionally, it's nothing to worry about. However, if you did not, your computer may have been harmed.

    In case you doubt your computer has been harmed by virus, you may do following steps to check.

    1. Scan your system
      1. Do a fully system scan by Windows Security
      2. Do a fully system scan by Malwarebytes
      3. Do a fully system scan by Norton Power Eraser

        Disclaimer: Microsoft provides no assurances and/or warranties, implied or otherwise, and is not responsible for the information you receive from the third-party linked sites or any support related to technology.

    2. Check if any unknown or suspicious programs are launched at startup
      1. Open Task Manager, go to Startup tab and disable unfamiliar entries
      2. Download and use Autoruns to check further
    3. Clean install
      Even if fully system scan can find and fix threats, you should do a Clean install as they may have made unrestorable changes to your system.

    Disclaimer: At this point, we have exhausted all troubleshooting and I recommend that we try to perform a clean install to get your computer back into a working condition. Please ensure that you backup any important data, including Documents, Pictures, Videos, and more. After that, you can find instructions on how to install Windows 10/11 in the following article by MVP Andre: How to: Perform a Custom Installation of Windows 11 and Windows 10 - Microsoft Community

    I hope that above information is useful to you.

    If you have further questions, please feel free to ask me by "Comment".

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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  3. AI answer

    2025-11-09T12:57:36.1666667+00:00

    The issue you're experiencing with the popup asking what software to use to open a DLL file typically occurs when the system does not recognize the file type and defaults to prompting you for an application to open it. DLL files (Dynamic Link Libraries) are not meant to be opened directly by users; they are used by programs to perform various functions.

    To resolve this issue and prevent the popup from appearing:

    1. Check File Associations: Ensure that the file associations for DLL files are correctly set. You can do this by right-clicking on a DLL file, selecting "Open with," and then choosing a different application or setting it to always use the appropriate program.
    2. Avoid Opening DLL Files: Do not attempt to open DLL files directly. Instead, ensure that the programs that require these DLLs are functioning correctly.
    3. Scan for Viruses: Since you mentioned concerns about a virus, it would be wise to run a full antivirus scan on your system to rule out any malware that might be causing this behavior.
    4. System Restore: If the problem persists, consider performing a system restore to a point before the issue began, which can help revert any changes that may have caused the problem.

    If the problem continues after trying these steps, you may want to consult with a technical expert for further assistance.

    AI-generated content may be incorrect. Read our transparency notes for more information.

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