Firefox crashes when viewing Youtube videos

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Crash signatures ( what's this? ): NPSWF32.dll

If Firefox is crashing when you try to view videos on YouTube, it is usually caused by the Flash plugin conflicting with one of your extensions.

Note: This article applies to the Windows version of Firefox only. For Flash related crashes on Mac OSX, see Pages that use the Flash plugin crash on Mac.


Update Firefox

Firefox 3.6.4 and above load plugins separately from Firefox, allowing Firefox to stay open if a plugin crashes. To make sure you are using the latest version of Firefox, see Updating Firefox.


Conflict with extensions

Firefox extensions can cause this crash. To test whether your crash is happening because of an extension, try launching Firefox's Safe Mode:

At the top of the Firefox windowOn the menu bar, click the Help menuFirefox button, go over to the Help menu and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
For Windows XP, click the Help menu and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.holding down the option key while starting Firefox.quitting Firefox and then going to your Terminal and running: firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox-4)
At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit. Then in Windows, click Start, open the All Programs list and navigate to the Mozilla Firefox folder. In the Mozilla Firefox folder, select Mozilla Firefox (Safe Mode).Then hold down the option key as you restart Firefox.Go to your Terminal and run: firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox-3.5). Firefox will start up with the Firefox Safe Mode dialog.
Note: You can also start Firefox in Safe Mode by clicking Start, selecting Run (or use the Start Search box in Windows 7 and Vista) and then entering the following in the text field: firefox -safe-mode

  1. In the Firefox Safe Mode dialog, click Continue in Safe Mode.
  2. Attempt to view videos to test for the crash.
    • If the problem does not occur in Safe Mode, an extension is likely the cause. To narrow down which extension is causing problems, see Troubleshooting extensions and themes.
    • If the problem still occurs in Safe Mode, follow the instructions in the next section of this article.


Flash plugin

The NPSWF32.dll file is associated with the Flash plugin. If the crash still happened in Firefox's safe mode, try uninstalling and re-installing the Flash plugin:

  1. For instructions on uninstalling the Flash plugin, see Adobe.com's article on uninstalling Flash.
  2. To re-install Flash, go to the Adobe Flash Player download page.
  3. Click the Download now button to download the installer.
  4. After you've downloaded the installer file, double-click it and then follow the on-screen instructions.
  5. Restart Firefox.
Contributors to this page: ThomasLendo, Tonnes