Potential solution for windows for a side-by-side install. This works for me.

To setup a firefox install side by side so that links from external programs (like email) can open (so you don't get a "Firefox is already running but is not responding" message) do the following.

The solution entails the use of the -no-remote switch. Don't use it for the default browser. Use it for the non default browser.

I'll use firefox 3.6 and firefox 4.0 as examples but this should work for future versions.

+ Install firefox 3.6 and Firefox 4.0 in different directories. Eg.

C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\Mozilla Firefox 4\firefox.exe

+ Open profile manager. Start > Run : firefox.exe -ProfileManager

+ In profile manager create Two Profiles.

   firefox3.6
   firefox4

+ In profile manager select firefox 4 as your default (assuming you want to default to the latest) and tick "Don't ask at startup"

+ Create two windows shortcuts.

• General: Mozilla Firefox 4 (default). Shortcut > Target: "C:\Program Files\Mozilla Firefox 4\firefox.exe". Shortcut > Start In: "C:\Program Files\Mozilla Firefox 4"
• General: Mozilla Firefox 3.6. Shortcut > Target: "C:\Program Files\Mozilla Firefox\firefox.exe" -p firefox3.6 -no-remote. Shortcut > Start In: "C:\Program Files\Mozilla Firefox"

That's it. Links from external programs should now open in your default browser.

Further details see. Opening a new instance of your Mozilla application with another profile

I have 4.0 installed in parallel to my 3.6 with different launch scripts and profiles. I am running on Fedora 14 (Linux). I have also noticed that it is narrowed down to only my email client, web links provided in LO documents or PDFs, or other apps work as before.

Glad to read it is only your email client. Have you tried another email client for elimination purposes? Perhaps your firewall is blocking links opening from Thunderbird.

It works fine with FF3.6 only have a problem with FF4.0. I haven't tried another email client yet. We are in the process of moving so I'll try that after the move this weekend.

My guess is that the way T'Bird passes the URL to FF may be acceptable in 3.6 but something changed with 4.0 so I have also posted this problem on the T'Bird forum as well.

I do not understand the answer. Is there some setting I can change to allow the linked PDF's to open? I dont want to have to open a second browser version just to read a PDF!

Larry, I was referring to when I open a PDF file in either evince or adobe and the document has embedded web links (URLs), I have no problem. The problem only happens when I do the same from Thunderbird. That was only why I mentioned anything to do with PDF's. When I click on an email message that has an embedded web link (URL), I expect it to open a new tab within the open FF window with the URL from the link. What I get is a 2nd copy of FF launched to my home page and is minimised. This only happens with FF 4.0 not FF 3.6,,,,,,,,,

larryamarks, my potential solution was for the case where a person needs to have two browsers installed. Web developers need to do this to test their web pages. If you only need one browser (and are having problems) then, yes, you ought not install a second browser.

Which browser are you using? Do links in your email client open a browser tab OK?

Does this work for 9.01?

Yes it currently works with Fedora 16 the LXDE desktop environment, FF 9.0.1 and T'Bird also 9.0