I have not noted this particular problem before, but it may have occurred on other web-site. I have had problems with web-sites not loading, but nearly always with a message at the bottom of the page that reads "Waiting for s7.addthis.com" (or "Waiting " for something else). There may have been times when a page did not load and the "Waiting " message was not there, but I have not noted those.

-> Error loading some websites

• http://kb.mozillazine.org/Error_loading_websites#Error_loading_some_websites

Try performing the suggestions mentioned in the following articles:

• Firefox and other browsers can't load websites
• Websites don't load - troubleshoot and fix error messages

Check and tell if its working.

Thanks again for your involvement. It's late here, so that is work for tomorrow. Do you have the IP address (e.g. 74.125.53.99 for Google) for the Add-ons site?

63.245.217.112 addons.mozilla.org

not sure

• http://websiteipaddress.com/Site/addons.mozilla.org

It's a late start this evening: I will not get much done. I tried using the IP address to get to the Add-ons page but the page did not open. Also, I opened Firefox under the new profile I created yesterday. As before. in the "about.config" page, typing "xpinstall." resulted in the list being reduced to 4 entries (5 under the old profile). None of them have the "enabled" extension. All of them contain "whitelist" in the name. Typing "xpinstall.enabled" results in an empty list.

Type about:config in the Location (address) bar and press the "Enter" key. When you see a warning, click I'll be careful, I promise! button.

-> right-click somewhere, click New -> select String

• name it xpinstall.enabled and set the value to True

-> Close the about:config tab and then Restart Firefox.

All the downloads should work now. If you delete this value some time later it still works.

Check and tell if its working.

Did that. Closed Firefox and opened it. Went to about:config and confirmed that Xpinstall.enabled was present with a string value of true. Tried to get to the Add-ons site using your link, my bookmark and through Tools/Add-ons, but all to no avail: still no web-page opens.

It's late now. Tomorrow, I'll look at the suggestions in the articles you provided yesterday. Thanks again

That is probably just a server problem. The Add-ons servers are sometimes overloaded and don't respond. I've seen at times that is can take minutes to download an extension or install it directly, even by using the right-click context menu with Save Link as. Just try it another time later or the next day if it happens again. I'm on Linux and on that platform you do not get a connection timeout after 20 seconds.

Thanks for that cor-el. I have tried the last few evenings to get onto the Add-ons site, but without success. I have on a couple of previous ocassions got through to the site but then have got the "0 bytes . . . "message. Maybe with the changes I've made at the suggestion of mha007, if I was now to get onto the site, the downloads might work. Over the next few days, I will try at different times of the day. Maybe evenings here (in Ireland) are a bad time for the servers. Other than trying to get onto the site, I've not worked on this issue this evening and it's late now. But I'll be back!

2 things to report. I have tried at various times today to get to the Add-ons site but to no avail. Also, I remembered another site that I had a similar problem with - expedia.com (and expedia.ie). Expedia is a big player in the travel industry. I have also tried to get to this site at various times today, but again, to no avail. I get a message at the bottom of the screen "Waiting for expedia.ie". I should point out that I am largely ignorant of Firefox. I installed it. It worked. "If it aint broke, don't fix it" is a motto I work to, so not until now have I had to explore the system. There may be something very basic that I am not aware of that, if changed, could fix it.

This evening I'll have a look at some of the suggestions that mha007 provided a couple of days ago.

Both of the links you provided expedia.com and expedia.ie are opening readily on my system using Firefox 10.

-> Update Firefox to the latest version 10

• How to install Firefox on Windows
• Websites show a spinning wheel and never finish loading

If you face further problems connecting to these websites, try to disable your security softwares, restart your system and then start Firefox (or other browsers) to open the websites on which you are having problems.

Check and tell if its working.

See also:

• http://kb.mozillazine.org/Error_loading_websites

A possible cause is security software (firewall) 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 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

I upgraded to Firefox 10, turned off Avast Web-shield, restarted the computer and opened Firefox. Neither the Firefox Add-ons nor the Expedia pages opened.

Mha007, can you confirm that xpinstall.enabled should be of type String? Most about:config entries with value "true" are of type Boolean. If it should be Boolean, how do I make the relevant change?

In Firefox/Options/Advanced/Encryption/ViewCertificates/Servers, there is an "addons.mozilla.org" entry under "The USER TRUST Network". Is this as it should be?

There are a lot of potential sources of the problem in the links you sent to me mha007, many of them in areas of which I am ignorant. After a couple of hours of reading I haven't got through all of them and it's hard to know where to start.

Currently, I've set Avast to run a full system scan.

That's it for tonight. Thanks to you both for your inputs.

-> Can you confirm that xpinstall.enabled should be of type String? Most about:config entries with value "true" are of type Boolean. If it should be Boolean, how do I make the relevant change?

• Try creating a Boolean preference by the name xpinstall.enabled and set its value to True

-> In Firefox/Options/Advanced/Encryption/ViewCertificates/Servers, there is an "addons.mozilla.org" entry under "The USER TRUST Network". Is this as it should be?

• leave it as it is. I also have the same certificate.

Check and tell if its working.

The pref xpinstall.enabled should be a Boolean pref and not a String pref.
You can either reset the pref to the default to remove it to make it hidden again, which gives it the true value.
If that pref is disabled the you get a sliding bar at the top to ask for permission anyway.
The not changing 0 bytes text is very likely a server problem or you have security software that is blocking it.
I've seen such a stalling on some occasions as well and you can only be patient is cases like that and try again later if Firefox aborts the loading.

I can see no way of changing the Type of a preference, nor can I see a way of deleting one so that I can re-enter it with the correct type. When I right-click xpinstall.enabled and select Modify, I am only given the option of changing the String value. In my efforts to change its type I right-clicked xpinstall.enabled, selected New/Boolean and typed True. However, this resulted in creating a new preference with the name True. I don't know how to delete this preference.

Note that I have made dozens of attempts to access the Add-ons site since I last managed to access it and I am unable to access Expedia. So I have 2 issues: accessing some sites and separately, downloading from the Add-ons site.

I'll be at the computer only intermittently over the next few days.

If you reset such a pref that has the wrong type via the right-click context menu (Reset) then that pref will be removed if you close and restart Firefox.
You do not need to re-add that pref as a Boolean pref because if that pref is missing the Firefox assumes the default true value.

I looked at "Troubleshooting network connection problems" at Microsoft.com (the page took several minutes to open). I don't think that the problem is with the network connection.

I tried to open the "Troubleshoot internet connection problems" but got "Problem with connection" / "The connection was reset . . .".

I've read a number of Mozillazines (each of them took some minutes to download).

In about:config, I entered a preference xpinstall.enabled of type boolean with value true.

In Tools/Options/Content, I un-ticked "Enable Java scripts".

In Tools/Options/Advanced/Network/OfflineStorage, I cleared cache (I have done this before recently).

In Tools/Options/History, I changed History/FirefoxWill: from "Remember history" to "Use custom settings for history", I clicked ShowCookies and removed all cookies. (I had selected cookies when I recently ClearedRecentHistory: surprisingly, there were a number of cookies present from Expedia before I removed cookies just now.)

I closed Firefox, rebooted, opened Firefox, tried to open the Add-ons and Expedia pages, but to no avail.

In Windows Systems logs (Start/Run/eventvwr) under Applications, there is a frequent occurrence of an Error for Source: PerfNet of Event:2004. Does this throw any light on the issues. I have checked PerfNet on a few forums but have not been much enlightened.

In the Firefox ErrorConsole (Ctrl-Shift-J), the error "server does not support RFC 5746, see CVE-2009-3555" is reported 5 times by developer.mozilla.org and twice by statse.webtrendslive.com. Is this of any significance?