The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

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Also having the same problem. Get the 'can't find server at' several times during the day' and have never had a problem like this in the past on Firefox.

Usually just clicking try again once loads it properly, but it happens so many times it gets annoying.

For me it began happening just before the 19.0.2 update too so not sure it was the culprit.

I haven't installed anything new in the past week so not sure why it has begun happening. And other browsers are okay, also ran Malwarebytes and nothing was found.

The reset didn't fix it just tried it a while ago.

A possible cause is security software (firewall,anti-virus) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

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.

I had already uninstalled Zonealarm, used clean.exe to make sure its all gone and then re-installed the latest v to make sure it recognize FF19. I've also cleared my Cache and done reset - no help

Any suggestions - its driving me batty :)

It was doing the same to me on www.usbank.com, even with fresh installs and clean profiles. It definitely started with 19.0.2.

We finally figured out the pattern. It only does it on 64bit computers. 32 bit computers don't seem to be affected, as they can go to usbank.com just fine. The 64bit systems just hang and wait.

No solution, but I have a feeling that's the pattern.

mackilvane: You're definitely on to something here. The culprit is the combination of Windows7 on a 64 bit PC and Firefox 19.0.2. All browsers use a unique useragent string that identifies not only the browser version, but also the operating system and specifics about the computer. Users are also reporting issues trying to access msdn.microsoft.com with the same hardware and Firefox version. My suggestion is to downgrade to Firefox 18 until Firefox has this issue resolved.

Hi mackilvane, there is a workaround for the US Bank problem in this thread: Bank website tries to connect but nothing. Works on Chrome & IE.

I'm on a 32bit PC with XP so the problem is broader than that

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.

I also experienced this issue for over a week, and it also started on my Windows 7 64-bit PC shortly before the release of 19.0.2, but everything has been fine for the last few days. I've frequently visited the websites that most often suffered from this error and they've all loaded just fine. I'm not sure whether a recent Windows update fixed the problem or if it was something else, but I hope the rest of you find a solution soon.

I went nearly a whole week without experiencing the problem, but it's back again. The only change I've made to my PC in the last 24 hours is a large update to Avira.

Also, sorry for making a second post and not editing my first one. I didn't notice the edit button until after I'd submitted this post.

This problem also seemed to go away for a week in my case, i thought it had to do with Windows Updates as well.

Now it is back and more annoying than ever -_-

Has anyone experiencing this problem had any luck finding a solution? This problem is becoming very annoying.

No - and YES very annoying

Whenever Firefox starts showing missing HTML on any pages I open, then I open Options > Advanced > Cached Web Content - Clear Now

It works until I reach about 140MB (although I have an override of 1000MB available). It's really odd.

Still having problems even after updating to Firefox 20. I take it nobody's had any better luck?

Still the same problem after new update. No one seems to have a clear solution...