How to fix invalid file extensions

Written by kevin boone
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Over time, invalid registry entries, including file associations, accumulate and slow down your computer. These entries occur as files are moved, deleted, created and modified; uninstallers can leave program traces in the registry. It is too tedious and dangerous to manually go through the registry to pick out invalid entries; a registry cleaner program is the best way to fix invalid file extensions and associations. These utilities balance effectiveness with safety and also delete temporary files.

Skill level:

Things you need

  • Registry cleaning utility

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  1. 1

    Go to, click "Download" and select the site you want to download from (Pyriform).

  2. 2

    Activate the installer (ccsetup---.exe, where "---" is the version number) and follow the instructions.

  3. 3

    Select the language and click "Next"; read the End-User License Agreement (EULA), click "I Agree," then click "Next." Select "Next" on the install folder; select the install options you want (the Yahoo! Toolbar is optional); click "Install."

  4. 4

    Check the "Run CCleaner" box, and click "Finish." CCleaner will activate. Select "Options" in CCleaner; click on "Settings" and check the desired options.

  5. 5

    Select "Advanced" and check "Hide Warning Messages"; check the desired options. Check all boxes under the "Windows" tab except for "Custom Files and Folders" and "Wipe Free Space."

  6. 6

    Check all boxes under the "Applications" tab. Click "Run Cleaner." This may take one or two minutes. Click "Registry" on the left side; check all boxes (including "Unused File Extensions").

  7. 7

    Click "Scan for Issues"; when CCleaner finishes, select "Fix all Issues." Close CCleaner.

    Auslogics Registry Cleaner

  1. 1

    Go to and click on the "Free Download" link for or directly from the site.

  2. 2

    Follow the installer instructions; click "Next," read the EULA, select "I accept" and click "Next." Click "Next" on the install options; click "Next" on the Install folder options; click "Install."

  3. 3

    Check the "Launch Auslogics Registry Cleaner," then click "Finish." Registry Cleaner will activate.

  4. 4

    Select "Quick Scan." When the scan completes, select "View Detailed Results" to see what has been detected. Click on "Fix." When finished, close Registry Cleaner.

    Glary Utilities Free

  1. 1

    Go to, navigate to Glary Utilities Free and select "Download Now."

  2. 2

    Activate the installer (gusetup.exe) and follow the instructions. Select the languages and click "Next"; read the EULA, check "I Accept..." and click "Next."

  3. 3

    Uncheck the "Ask Toolbar" options (the Ask Toolbar is optional). Click on "Next," then "Next," click on desired options, then click "Next" again. Click "Install."

  4. 4

    Restart your computer if prompted to do so. Launch "Glary Utilities," click on "Cleanup and Repair," then "Registry Cleaner."

  5. 5

    Check all boxes, including "File Associations" and "File Extensions." Click "Scan Registry for Problems. Click "Repair Registry." Close Glary Utilities.

Tips and warnings

  • CCleaner is voted the best cleanup utility by the users of Techsupport Alert website.
  • Auslogics Registry Cleaner has two modes: "Quick Scan" and "Advanced". Quick scan looks for 12 registry areas, including invalid file extensions and associations. The advanced mode looks at 4 additional registry areas. Auslogics Registry Cleaner backs up the registry before activating.
  • Glary Utilities has advanced features including temporary file deletion and a duplicate file finder--use these modules with caution, as misuse can cause instability issues.
  • Manually editing the registry is dangerous, even for experienced technicians. Improperly editing the registry can cause system instability or render the computer unbootable.

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