I think it's Google that's making it freeze, because this happens to me whenever I try to search something with it or login to Gmail.

I had the same problem. If I did a search from Firefox search toolbar via Google, Yahoo or Bing or tried to go to Google to access G-mail, my browser froze as you described. I uninstalled FF 4 Beta and will wait until it is out of Beta before re-installing.

I had the same problem so I tried installing firefox 4 on another computer in the same house with no luck.

Then I started firefox with a new tab and went through my add-ons. The problem was McAfee Siteadvisor. It must not be properly compatible with Firefox 4 yet. After disabling it, everything works fine including yahoo search, bing, and nanoc website.

Thank you SO much, yes McAfee Siteadvisor is the problem, now that I disabled it firefox is working perfectly which is great, because for some reason chrome doesn't work with things like facebook chat or google translate for me

Yes, McAfee still the incompatibility issue - now with yesterday's release candidate.. Just disabled all addins and then started adding them back. Site adviser crashed firefox 4RC1. When disabled all is OK . This is an important addin so a big concern. Obviously nothing has been done since the earlier reports.

mozilla needs to fix this before release.

I was actually having this same problem with the latest 3.X version (3.17?). That's why I switched to the 4.0RV version but no luck. Just recently updated Flash. Also running McAfee. Running Win7 on a 64-bit machine. My home page is Google so that's what comes up when I start Firefox.

I had the same problem, so I use back v3

I tried that, too, and now version 3 does it! I have no ideas, since the browser is basically useless after it's been open for twenty seconds.

I had the same problem and solved it, my resolution is disable Norton IPS add-on which is not compatible with FF 4 yet

Worked for a while today after upgrading to 4. Now freezes up upon opening. Can not use. Useless! So I see a lot of people with the same problem. But no solutions.

Conduit engine disable. Problem went away.

This happens to me only after viewing a PDF.

I found that I could "unfreeze" FireFox by selecting something from the File menu like "Save Page As..." and then clicking Cancel.

I think the problem started for me when I installed Adobe Reader X and before installing FF 4.0.

Note: I don't have McAfee or Norton antivirus.

I had the same problem from the get go and was so frustrated I was going to go back to version 3. However yesterday I ended up downloading version 4 once again and installed it over the original version.......have been heavily using the my Mac Book Pro since the re-install and it has not frozen once......works for me and it might for you too. thanks Ken

disable the conduit engine. i tried disabling my add-on's in turn, and disabling the conduit engine was the one that worked

in about:config dom.ipc.plugins.enabled=false helped me

Hi, i had the same problem, using Bullguard antivirus, I contacted them, just received answer, . It is incompatibility of FF4 and bullguard (they know about it, and fix will be released soon), and probably most of the other antiviruses, as I see this is very popular problem. The solution though is simple : in firefox disable addon bearing your antivirus name or any "safe browsing" one. It works.

Hi, I have the same problem. Firefox 4, Windows Vista, Windows Media Player 11. If I have Firefox and Media Player open at the same time, and I right-click on an image or something and Save As, Firefox will freeze. It will stay frozen until I close Media Player. As soon as I close Media Player, Firefox picks up where it left off and opens the Save As dialog box.

To all the Firefox users, who updated to FF 4 and have been pulling their hair apart for FF crashes.... The culprit is not FF but the Antivirus tools we use that also install the Antivirus toolbar.. disable it and FF works like the old charm again...

do you know that your harddisk make it freeze take a bit moment and hear your harddisk make a click sound try intalling mozilla on another harddisk not in program files this help me alot and my firefox lightning fast and i reinstall my window xp on harddisk D not C and no more click sound because i dont use harddisk C that produce click sound and another program work well!!!