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I have been using Firefox 3.5.7 very happily for months now. It lived happily with IE on my syatem as well. However, I upgraded to Firefox 3.6.3 this past Friday, and now Firefox wil tun run. It locks up. Please tell me where to go to get a copy of 3.5.7

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My Firfox 3.5.7 was running like a bandit. I ,upgraded up to 3.6.3 , and it has brought my system to its knees. Please help me get back to a very happy Firefox user

After I download Firefox 3.6.3

User Agent

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) ; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)

My Firfox 3.5.7 was running like a bandit. I ,upgraded up to 3.6.3 , and it has brought my system to its knees. Please help me get back to a very happy Firefox user == After I download Firefox 3.6.3 == == User Agent == Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) ; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)

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3.5.x will be supported until August.

http://www.mozilla.com/en-US/firefox/all-older.html

Also see: Install an older version of Firefox and Installing Firefox

If you want to troubleshoot your problems with Firefox 3.6.x you can start with Firefox hangs or is not responding - How to fix. Start basic troubleshooting with Diagnose Firefox issues using Troubleshoot Mode.