Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Firefox install causes error messages during startup and freezes during running

  • 7 replies
  • 3 have this problem
  • 7 views
  • Last reply by gouber80

more options

I installed firefox 20 on Windows 7 and when I reboot I see several messages telling me that I am missing dll files. I have verified that all the dll files are in the install folder. I was able to run firefox without running firebug and just putting up with the annoyance in clicking ok ont he messages at the start. However when I installed firebug and tried to start I have not been able to use the browser since.

I installed firefox 20 on Windows 7 and when I reboot I see several messages telling me that I am missing dll files. I have verified that all the dll files are in the install folder. I was able to run firefox without running firebug and just putting up with the annoyance in clicking ok ont he messages at the start. However when I installed firebug and tried to start I have not been able to use the browser since.

All Replies (7)

more options

Is this already appearing during the boot process or only after starting Firefox?

You can use the MSConfig program or the Autoruns utility to see which software and services are getting started.


Do a clean reinstall and delete the Firefox program folder before reinstalling a fresh copy of Firefox.

Download a fresh Firefox copy and save the file to the desktop.

Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.

  • Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will also lose your personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

Your bookmarks and other profile data are stored in the Firefox Profile Folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.


more options

Thank you for responding, here is more information about the issue.

The error messages that I see are during startup. There are 6 messages stating that the following 5 dlls are missing.

mozglue.dll nspr4.dll x 2 messages plc4.dll mozsqlite3.dll nssutil3.dll

Whenever I start FF now, I see a message asking if I want to start in Safe Mode or Reset FF. I first tried to start in SM, same results. I then did a reset. Even after the reset it has the restore session. I ignore that and attempt to navigate to a public site (say google or msn). Any action including closing the restore page causes a (Not Responding) message added to the browser window and I am forced to close it.

more options

I forgot to mention that I did a security scan based on the steps from this support issue

more options

If there is a problem with files in the Firefox program folder then you need to do a clean reinstall and delete the Firefox program folder.
Firefox Safe Mode or a reset won't help in this case.

more options

Thank you for the suggestion, here are all of the things that I have tried.

A full uninstall did not do the trick. I checked the program folder but was already deleted. I tested this a few times and the same result happens each install. I downloaded the install from here the FF home page. Just in case I had a bad dl, I re-downloaded the install file and still the same.

I installed FF with FireBug on another Windows 7 machine and all went well. I also tested a VM of Server 2008 and everything went well there. I also have Window 7 @ work and I am pretty sure I have firebug, I know I have both FF and Firebug on the vm of Server 2008 @ work and those work well too.

Do you know of a way that I can look at logs or some other way to diagnose this?

Modified by gouber80

more options

P.S. I just noticed that uninstalling with the preferences not checked did allow me to access the browser. I still have the dll errors at startup though.

more options

As for the Autoruns utility, under the Everything tab, I only saw an exe for the Mozilla Maintenance program. Nothing that called those dlls or the FF startup. Should I check for something else there?