We're sorry to hear that your Firefox seems to be crashing when you open it. Please perform the following steps to give us a crash report ID that helps us find out more about the cause of the crash.

1. Press the following shortcut to get a Run window: [Windows] + [R]. This should bring up a window that contains a text field.
2. In that text field, enter %APPDATA% and press Enter. An explorer window should open.
3. From that explorer window, double-click on the Mozilla folder, then double-click on Firefox and then on Crash reports. Double-click on submitted.
4. Now, you should see a list of files that contain reports. Go to View > Arrange Icons by > Modified to get the most recent files at the top of the window.
5. Open the most recent 5 files with a text editor and copy the IDs.
6. Paste each ID into the reply window on the forums.

You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

I would, but there's nothing new there. Only reports from back in September. I opened Nightly and it seems to only crash when I got to gmail and iGoogle. Other sites seem to work (though half the time Nightly gets sluggish).

Ya, we got some problem before two days, ie., when you open gmail Firefox nightly crashes. but now its solved. Update your nightly and check it out...

I updated this morning and that's when it started crashing, but I'll try updating again...

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

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) and confirm all upcoming messages.
3. Now, uninstall Firefox by following the steps mentioned in the Uninstall Firefox article.

IMPORTANT: On Windows, the uninstaller has the option to remove your personal data and settings. Make sure that you do not check this option; otherwise all of your bookmarks, passwords, extensions, user customizations and other Firefox user profile data will be removed from your computer.

After uninstalling Firefox on Windows, delete the "Mozilla Firefox" program folder, located by default in one of these locations:

• (On 32-bit Windows) C:\Program Files\Mozilla Firefox
• (On 64-bit Windows) C:\Program Files (x86)\Mozilla Firefox

1. Go to the Windows Start menu and click on "Computer".
2. In the Explorer window that opens, double click Local Disk (C:) to open the C:\ drive.
3. Find the "Program Files (x86)" folder or "Program Files" folder.
   • On 32-bit Windows, double-click the Program Files folder to open it.
   • On 64-bit Windows, you will see a "Program Files (x86)" folder AND a "Program Files" folder. Open the Program Files (x86) folder.
4. Look for a Mozilla Firefox folder. If you find one, right-click it and select Delete and confirm that you want to move the folder to the Recycle Bin.

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.

The (never really supported) Win64 nightly channel builds (which gets updates each day) have been more crash prone in the last while ever since the code merge/move on the channels a week ago. The Win64 does not get supported like the Win32 and the 32/64-bit Mac and Linux builds so any regressions or server issues and such for WWin64 can take a while to be fixed if ever. Especially in next while as Mozilla is planning to not focus on the Win64 nightly much for the time being.

The Win64 builds were really more for to catch breakage/regressions since it is possible to affect Win64 without affecting the Win32 however far too many users have been using them in thinking they were a better option for their 64-bit Windows.

It's rather disheartening as I prefer to use Mozilla over IE on my work computer. The company got me a new computer about a year a go (Win64) and I was annoyed to find out that I had to use Nightly instead of Firefox. Even more so now with the crashes and such.

I went in to check which version Nightly had updated to this morning and as I was checking it started to perform yet another update. It has now stopped crashing when going to gmail.

You do not need 64-bit builds to use Firefox on 64-bit Windows as the 32-bit builds of Firefox works fine if not a bit more faster and stable.

We've tried multiple times to get the 32-bit to work, but it won't. It will download but refuses to open.

Also, Nightly updated this morning and now it won't even turn on. Seriously, this is enough to make me give up on Firefox altogether.

Edit - I uninstalled nightly and reinstalled. It's at least opening now.

Nightly builds are meant for Testing and not for stable use like the Release builds are like 17.0.1. The Nightly channel gets checkins pretty much every day so therefore it gets a update each day which can occasionally make it more unstable for some until it is fixed, usually by next day or two or longer if you are using the experimental Win64 builds.

Did you try a new profile with the Nightly build to be sure that it isn't caused by something in your current profile.

You may also need to disable hardware acceleration or just start in Safe mode to see if that helps.