We're sorry to hear that Firefox is crashing. In order to assist you better, please follow the steps below to provide us crash ID's to help us learn more about your crash.

1. Enter about:crashes in the address bar (that's where you enter your website URL) and press Enter. You should now see a list of submitted crash reports.
2. Copy the 5 or more most recent crash ID's that you see in the crash report window and paste them into your response here.

More information and further troubleshooting steps can be found in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

"Submitted Crash Reports No crash reports have been submitted."

Yup... just tried again... same thing, same non-existent crash reports. Worth bearing in mind: on this W7 64-bit OS, things WERE working OK for a long time... I'm doing a manual install of many things one by one. In fact I'm making Macrium disk images every so often, so the nuclear (undesirable) option is to go back to the last one and re-do things, monitoring FF's crashing as I do. Far better however to find out what the problem might be. Seems to happen with rather more complicated web pages...

You need to submit/report crash reports first, see Mozilla Crash Reporter.

No, let me be clear: I am not getting ANY dialog box when it crashes... the entire window just vanishes in a split second without any warning or anything happening afterwards. Sometimes when I start up FF again I get the "Well this is embarrassing" page, but not always

Is the problem specifically after the download starts, or even when you try to open this page: http://www.apachefriends.org/en/xampp-windows.html

Sometimes inexplicable crashes can be caused by damaged program files, due either to random glitches or malware modifications.

Can you back up your Firefox settings folder (profile folder) and do a clean reinstall of the Firefox program files?

Regarding backup: Back up and restore information in Firefox profiles (this is for emergencies, a clean reinstall doesn't actually remove this folder)

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 https://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 or rename the Firefox program 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.

Does Firefox run any better?

thanks for that comprehensive reply. To answer your first question: what's funny is that if I just copy that link from IE (which I'm necessarily using at the moment unfortunately) to FF, it goes to the Xampp download page. However, if I do a google search for Xampp, the first link is to that page... but once I click the link FF vanishes in the blink of an eye. What to make of that?? Anyway I'm going to carefully follow your recommendations. For the record I have already done several uninstalls of FF followed by reinstalls, usually rebooting as I go... but the journey of a thousand miles...

later...

whoops, no joy. Totally clean uninstall. The FF directory completely removed. Even removed the Mozilla "Maintenance" directory for good measure. Rebooted. Totally new install. Clicking that Xampp link after the google search resulted in same old crash.

NB since my latest Macrium disk image (although obviously the offending step/app may have occurred before then) I have not installed much: Thunderbird however might be a possible culprit. The other thing is 7Zip (64 bit version). Also MS Security Essentials: could *easily* be a culprit. Bit like an Agatha Christie novel: whodunnit? They all seem innocuous but one probably has blood on their hands...

Except no: I installed MS Security Essentials *because* this FF crashing started to happen: scared it might be virus/malware. But after scanning my system was reported as clean as a whistle. Not surprising as I already had a firewall and Avira installed. Hmm... quite a puzzler

By the way, I'd appreciate any more ideas about this but as it's nearly 11 pm where I am I shall call it a day... thanks to you both for your help though.

What if you use a more obscure search engine such as Startpage?

https://startpage.com/

The reason I ask is that some malware intercepts the links of popular search engines and if this problem is limited to Google and maybe one or two other top search engines, then I would suspect you might have such an infection. You could try a rootkit scanner to see whether it finds anything that might be evading ordinary scanners.

TDSSKiller - AntiRootkit Utility

Thanks again... no joy... clicked the link in Startpage, FF crashed immediately

antirootkit: ran the latest version... no threats detected

Hi Mrodent, I realize this experimentation is very inconvenient.

To diagnose whether this is a problem in your settings, could you do another two-minute experiment?

Create a new Firefox profile

It will have your system-installed plugins (e.g., Flash), but no themes, extensions, or other customizations. It also should have completely fresh settings databases and a fresh cache folder.

Exit Firefox and start up in the Profile Manager using Start > search box (or Run):

firefox.exe -P

Any time you want to switch profiles, exit Firefox and return to this dialog.

When creating a new profile, I recommend using the default location suggested, and to avoid data loss, not re-using any existing folder. Before deleting unneeded profiles, I suggest making a backup first in case something were to go wrong.

Do links work in the new profile?

If that does not make any difference...

If I understand correctly, you can load pages by pasting in the URL bar, and presumably using bookmarks, but not by clicking a link in a search engine results page. Some related thoughts:

• Does this problem occur with all links from one site to another (search engine or not)? For example, if you are clicking from this post (on support.mozilla.org) to, say, http://kb.mozillazine.org/Knowledge_Base?

• Does this problem occur when following links that stay within the same site?

• Does it make any difference if you right-click the link and open it in a new tab or new window?

Hi, Honestly I wouldn't worry at all about me losing settings etc. Like I say, I'm re-installing my Dell machine from scratch with W7. This is sthg I always get around to doing with a new machine, and I have to prepare myself for essentially becoming a monk for several days or weeks, while I commune for hours at a time with my machine. Plus this is new architecture (x64) and new OS (W7). Thank you for continuing to have patience. But it could be important: I can't be the only person in the world to whom this has happened.

later

when I created a new profile (and then another) and tried to run FF it wouldn't run: nothing happened. The only profile which works is "Default". Whether or not I unclick "Don't ask...". In fact with the latter unclicked FF refuses to run.
Answers to your Qs:
- no it doesn't happen all the time... in fact when I first used the comp today I clicked on the Xampp link and it didn't crash FF. But now it happens all the time (again).
- same site: yes, sometimes.
- right-click: yes, sometimes a right-click (display in new tab or display in new window) can cause a crash.

later

Have now gone and uninstalled FF24 and reinstalled FF17.09. Seems rock-steady. No crashing. Have naturally disabled all automatic updating. If you are not completely exasperated by now perhaps you'd like to say whether it's possible to run two FFs simultaneously on a system???