I have the same problem. I usually have many tabs opened but the same amount has Firefox 3.6 handled without problems. After using Firefox 4 for some time, it freezes for a while, then works 30 seconds and crashes. It's very often just like that. I'm always sending bug reports with URLs and I hope this to be resolved quickly. It's unacceptable for such a browser like Firefox !

I Also Have The Same Problem But Just Started This Yesterday I Ran A Complete Scan On Computer And Nothing Is Showing Up But It Does Not Surprise Me At All I Also Have Explorer That Really Does The Same Thing But Explorer Is Worse That's Why I am Using Firefox Now I Have A HP Touch Smart. I Put Windows 7 Ultimate In It Now.I Also Have Another Computer That Explorer Freezes Up So Bad That Can't Even Use The Thing.Why Put Explorer In Windows If You Can't even Use It.

Yes, I also have found Firefox 4 to have a huge memory leak. Lots of people are saying it's due to add-ons. But most people have found that doesn't seem to be the problem. It has to be the inner workings of Firefox. It usually happens for me after I leave the browser open and put my computer to sleep and then turn it back on. It seems to drag and eat my CPU up to 250MB.. maxes out my CPU to 100%. have to restart computer.

Wow No Problem Like That Yet

Well It Happened Again Firefox 4.0 Crashed Again Over Night It Appears To Me That After A Certain Period Of Time Firefox Does This So I Put Back Firefox 3.6 And So Far So Good Strange But Not Surprised.But I Still Like Firefox But I Can't Use Explorer It's Much Worse.

Firefox has been crashing repeatedly for me for a year or two. During the Firefox 4 Betas it stopped crashing and I assumed it was fixed, but once the RC and final version were released it started crashing again. I've tried running it with all add-ons disabled but it still crashes. I'm getting fed up with supporting Firefox now if this cannot be fixed.

https://support.mozilla.com/en-US/kb/Firefox+crashes#Getting_help_with_your_crash

Type about:crashes in the URL bar and hit Enter.
Click the hyperlinks to bring up the Crash Report pages and copy'n'paste the URL of each of those reports into the message box here. We'll see if we can help you figure out what is causing those crashes to happen.

Did all of that. None of my crash reports had any references in the support file. In other word, every search came back zero. I can't be alone in all this. I've had no problems with firefox until I downloaded the new non-beta version. Now it's a toss up as to whether I'll get a session or have to reboot the computer. I don't have time or patience for this. No problems with any other browser and no problems with firefox on my laptop or netbook--same version. I downloaded and installed it again after the fourth lockup and crash this morning, but it crashed again the minute I tried to start it. Now I've got a perfectly good session going. Go figure. There has to be a fix for this!

I have a hp6710b and when I visit any site that has flash, including youtube, ff crashes.

It also happens with some pdf downloads.

https://crash-stats.mozilla.com/report/index/d4cb4535-682f-45ed-9205-d69142110719#addver

https://crash-stats.mozilla.com/report/index/bp-d4cb4535-682f-45ed-9205-d69142110719

https://crash-stats.mozilla.com/report/index/85dce30d-171a-4b57-bf82-e03f92110721

On another laptop with the same plugins, I have never had an issue. It is specifically with ff and some hp machines.

Since I posted my query, I've upgraded all three computers to FF 5.0.1. That solved 90% of the problems. I did have a couple of crashes on the Dell laptop a few days ago and solved it by loading without plug-ins then eliminating some of the plug-ins that did similar jobs just differently enough to cause a conflict. For instance, "Down Them All" seems to conflict with "FlashGot" on this computer. Got rid of both and the problems disappeared. FF 4.x (didn't matter which build) wouldn't even successfully open with the plug-ins disabled. Go figure. I think 4 had some serious issues that 5 took care of.