Sorry to hear it isn't working for you. I know everyone has different add-ons and sites they visit, so it's hard to compare experiences. (Works great for me.)

First, make a backup of your computer for safekeeping. To back up Firefox, see Backing up your information.

Next, download and save Firefox 3.6 to your desktop for future installation. http://www.mozilla.com/firefox/all-older

Close Firefox 4, and uninstall it. Do not remove your personal data and settings, just the program.

Then finally you can reinstall Firefox 3.6. Unless you have installed an incompatible add-on, it should pick up where you left off. If there are serious issues, please post back with details.

Note: I haven't actually tried this downgrade myself!

I did go back to 3.6 and every thing is running as it should. I think I will wait until all the kinks are worked in 4.0 out before I feel forced to using a beta version again.

I am having the same problems with FF 4.01. It freezes and Task Manager shows it using 48% of CPU with FindFast using another 48%. I am using XP Pro on a Pentium D dual core machine. I have re-installed 3.1.17 and the problems have disappeared.

FF 4.01 needs to go back to the drawing board to have the kinks removed.

FF 4.01 is not up to FF standards. The menu bar is a mess. The Bookmarks Toolbar is a mess. I used it for one day and was screaming at it. Went back to 3.6 and java is now loopy. Thanks guys, next time stop trying to be so fancy and stick with what works. I mean, the menu changes are not even logical. Bumper.

4.0 worked perfect. 4.01 NOT! I'm having all sorts of issues, from being slow, to having to accept every single page and worse, sometimes frames... I can't view videos on FBook. I tweaked it to view pix b/c I couldn't do that either (and it depended on what page of FB I was on, so I had to do this like three times) It even shows banks as not trusted. I want my 4.0 BACK! how can i remove the latest update 4.01? Anyone know?

BTW, I was using 4.0 with the format of 3.6. You can adjust its look and you don't have to go back to 3.6, however they messed it up when they went to 4.01

@janmarbol, can you start a new question with your system and add-on information?

Same for me. 4.01 is very slow, and Java stopped working. Am using Windows 7 professional. Switching to Opera until this is fixed, I don't have time for this!

Try changing the about:config settings.

Here's a summary of most of the config settings:

http://kb.mozillazine.org/Firefox_:_FAQ ... ig_Entries

Here's a useful Youtube tutorial on how to change some of the settings:

http://www.youtube.com/watch?v=wGYggczgyo8

and another website that describes some useful tricks:

http://www.techrepublic.com/blog/10thin ... -hacks/719

Geeky stuff, but my Firefox 4.01 did speed up. Turning on the pipelining feature makes a big difference.

@vrmgi, can you fix the first and third links in your post?

Actually, I found them:

About:config entries - MozillaZine Knowledge Base

10 handy Firefox about:config hacks | TechRepublic - 5/7/2009

(For messy URLs, you can use the TikiWiki syntax of [url description])

yeah same problem, my memory usage went from 75k with 3.6 to a staggering 250k with version 4. On top of this i had major hangs with cpu usage at 100% ( i actually felt sorry for my computer lmao)

Until the upgrade i never had a problem so i'm fairly dissapointed as i expected better from mozilla.

I've been to a number of forums and it seems like a common issue / fault.

Hope its fixed soon but until then i simply installed 3.6 over 4 and i'm back to normal (didn't even need to uninstall version 4).

myself was a FF user for last 12 yrs !! even i remember recommending ppl abt it...but FF 4 is a real PAIN IN THE APPROPRIATE PLACE....

it hogs memory...for simple functions (available by default in previous vers) ,now u have to install add-ons for them (like new tab button, FF4 either lets u have a new tab button OR the "+" button near opened tabs..but U CANT HAVE THEM BOTH SAME TIME!! WHAT THE.......

PC hangs/freezes almost everytime i ran FF 4 ..and for that i have lost valuable data..mind u, my machine config is not outdated. I have reverted back to previous vers FF 3.6...and am NOT UPDATING IT SOON....

ALL OF U FOLKS HAVIN PROBS WITH FF4 : easiest solution for all your probs -

1) get rid of FF4 and install the previous vers - http://www.mozilla.com/en-US/firefox/all-older.html after backing up - https://support.mozilla.com/en-US/kb/Backing+up+your+information

OR

2) get an alternative browser

yes folks, the above solution will at least give u peace of mind and a more peaceful good night sleep

This is an insult to you that you would coerce us to a beta or worse like M$. That causes my computer to crash seconds after I start Firefox 4.01. Yes my computer Kernel crashed a "blue screen of death" and otherwise works great, zero problems with 1500 MB RAM. I'm now using Opera to write this to you. Also am looking at other browsers too, since I now wonder if this will be worth using again. Certainly I'm irritated this caused delays and confusion. I drop programs for less, like IE. No kidding, I've backups, but honestly! Why did you have to kill 3.6 to upgrade to beta 401? The bridge back is gone.

Your "backup" doesn't include the tabs that I want to restore back into 3.6 Why would you risk your reputation to be like IE beta and lose? Supply quick resolve to restore your reputation with a; 1. Fix the problem to work proper again and notify us or 2. Enable me to revert back to 3.6 flawlessly, better than the move to 4, such as, that I don't I lose my tabs that I had to recreate upon "Upgrade-so-called" too. Since I don't see a clear remedy to this serious problem in this pile of other complaints.

@MrKeith, you should use Firefox's Profile Manager to create a new profile. If that runs correctly, you can import your bookmarks, saved passwords, saved sessions, etc. into the new profile.

(1) First, I recommend backing up your Firefox settings in case something goes wrong. See Backing up your information. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.)

(2) Fire up the Profile Manager to create a new profile: Managing profiles.

(3) Migrate key settings (be selective to avoid importing the problem): Recovering important data from an old profile.

Hope this helps.

How did you go about reinstalling 3.6 over 4.0?

Couldn't get 4.0 to work. I tried Firefox 5.0 and had even more problems. I finally gave up. My browser of choice is now Chrome. It's fast, everything works perfectly and I like the interface better.

Bye Bye FireFox we had a great 7 years together. My new love is Chrome.

Forgot to add... All my bookmarks transfered over seamlessly. I was up and running in minutes.