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Firefox does not start after choosing a user profile but does start if profile selection not done

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  • Last reply by alasdara

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When I select a user profile from the 'choose user profile' dialog box nothing happens. No firefox process shows up on task manager and no error messages are displayed. I can get firefox to run if I tick the 'don't ask at start up box' in the 'choose user profile' dialog, then select a profile (as usual nothing happens other than the dialog closing), then click the firefox icon and firefox starts. So firefox will not start only after a user profile has been selected. I've tried uninstalling, including deleting the Mozilla Firefox folder in program files and selecting the option to not keep user data. Re-installed firefox and got exactly the same problem. I've tried creating a new profile, no difference. I've also tried re-starting my computer several times. Firefox worked fine a few days ago. The problem started not long after I installed dropbox but I don't know if the two are related.

When I select a user profile from the 'choose user profile' dialog box nothing happens. No firefox process shows up on task manager and no error messages are displayed. I can get firefox to run if I tick the 'don't ask at start up box' in the 'choose user profile' dialog, then select a profile (as usual nothing happens other than the dialog closing), then click the firefox icon and firefox starts. So firefox will not start only after a user profile has been selected. I've tried uninstalling, including deleting the Mozilla Firefox folder in program files and selecting the option to not keep user data. Re-installed firefox and got exactly the same problem. I've tried creating a new profile, no difference. I've also tried re-starting my computer several times. Firefox worked fine a few days ago. The problem started not long after I installed dropbox but I don't know if the two are related.

Chosen solution

After booting the computer in safe mode firefox worked as expected again. I eventually traced the problem to comodo firewall. The Defense+ function had assigned the isolated application policy to firefox. Setting the policy for firefox to trusted application seems to have fixed the problem and firefox now runs fine :-)

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Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

  1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
  2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • Windows:
      • C:\Program Files\Mozilla Firefox
      • C:\Program Files (x86)\Mozilla Firefox
    • Mac: Delete Firefox from the Applications folder.
    • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
  4. Now, go ahead and reinstall Firefox:
    1. Double-click the downloaded installation file and go through the steps of the installation wizard.
    2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

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Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

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Chosen Solution

After booting the computer in safe mode firefox worked as expected again. I eventually traced the problem to comodo firewall. The Defense+ function had assigned the isolated application policy to firefox. Setting the policy for firefox to trusted application seems to have fixed the problem and firefox now runs fine :-)