there have been two dozens of security vulnerabilites fixed (half of them critical) in firefox since version 10, so you'd most probably be better off & safer with the latest version from getfirefox.com.

however if you still want to use a outdated version together with your security software, refer to the following help article: Install an older version of Firefox.

It would be possible to download and install Firefox 10. That however can not be recommended as it is insecure and unsupported.

• see installing a previous version of firefox

What is the protection software that you refer to, and is that up-to-date itself ? (If it is unable to handle the latest Firefox release that is hardly a good sign)

Thanks for your replies. I'm using Trend Micro that is up to date. When preparing to download Firefox ver 12, it gives a message that no Trend Micro plug-in is available for this version. I confirmed that with Trend Micro on the phone. It seems to catch everything over the years, so I don't want it unable to do it's job. Looks like I need to do some more research before I move ahead.

Actually it is safe to use the Firefox 10.0 if you resort to using the Extended Support Release ESR channel builds and not regular 10.0 release channel version (10.0.2 was last) as above were saying is insecure.

The 10.0.4 ESR is more for the Enterprise users in mind. The 10.0.4 came out when 12.0 was released.

Firefox 10.0.4 ESR http://www.mozilla.org/en-US/firefox/organizations/all.html https://www.mozilla.org/security/known-vulnerabilities/firefoxESR.html

Over time it may not be as safe as it may not be possible to back port all security fixes over the year until Firefox 17.0

Thank you James. I'm not there now, but will download soon. I'll be upgrading to ver 12 when Trend Micro puts out a plug-in for it. In the meantime, thanks for reassuring me, and letting me know which ver 10 to download.

Thanks again.

If you do use the 10.0 ESR you will need to install the current release in order to get back on the Release channel should you want to continue using releases again. There is a way to change the channel in a file however this install way is easier for most.

Thanks, James. I did download 10.4ESR and it asked me to enable the plugins that 12 doesn't currently work with. Seems everything works.

I think the official advice in similar situations maybe to use another browser !!
( Personally I have other Firefox versions and OS s available,and probably would consider ESR in this sort of situation)

It may also (as mentioned by Alice) be worth trying modifying the User Agent String that you present, when using Firefox, possibly by use of an add-on :

• https://addons.mozilla.org/firefox/addon/user-agent-switcher/

'I 'want to go back to 10 because it was pretty stable and 11 point whatever is driving me nuts. There are issues with adobe flash (had to back up and user an older version of 'that 'with 11) and now F.F. 11 is locking up I think a better idea is before releasing a new version *you* get all the bugs out before turning it loose.

The Adobe Flash 11.3 has been having issues with older versions of Firefox also and not just 13.0.1 or 13.0 as it seems like as Flash 11.3 was released a few days after Fx 13.0. If you have the Real player or the extension then that could be the issue. https://support.mozilla.org/en-US/kb/flash-113-doesnt-load-video-firefox

It is not like there were not any Beta test builds as there were seven for 13.0 and six for 12.0 and also RC builds for example. Also impossible to release a application with ahem no bugs ;).

Ever thought about going forward, not back !?

The Beta channel is stable, has improvements and new features,

• http://www.mozilla.org/en-US/firefox/channel/

and if you should encounter any problem you have a safe secure and fully supported alternative the ordinary Release channel !

You even get the opportunity to look for and report any bugs before the release.

(Once you have been on Beta for over 6 weeks you have already experienced the potential Release version prior to it morphing into a fully fledged Release, and so can be fairly confident that it will be trouble-free when it becomes the Release.)