When I look at certain websites, my computer will just freeze up for about 1 - 2 minutes. This generally will happen just the one time and then I am good for the day. The 3 sites I can remember off the top of my head are mlive, huffingtonpost and sbnation, but there are others.

Any idea how to prevent this?

Dell Inspiron 530
Intel Core 2 Quad CPU Q6600 @ 2.4 GHz
4GB Ram
Windows Vista
32 bit

I'm using Firefox 19.0.2 as a browser but I had the same problem when I tried Chrome.

Had the same problem with Firefox, the site that kept crushing was CNN
Do you use some kind of video blocker? I suspected that was my problem but could never confirm as I got tired from it and switched to Chrome (which apparently is holding up for now, no crashes, knock on wood )

No video blocker. I never even heard of that before. And I have no problem with the CNN site.

And the problem is not crashing. The computer just freezes and then after a while it works fine. After the freeze is over, all the programs I had open are still open and they work fine.

Sounds more like a failing hard drive than a problem with web browsing.

Have you run any SMART hdd monitoring software to check your HDDs?

No, I've never run that software. Which one should I use? Google shows a lot of possibilities.

Make sure flash and java are up to date. Disable all extensions in FF and see if it still happens.

Does FF still have a safe mode?

Pretty much any SMART software is good - all it is doing is reading SMART data from the hdd.

It can be common for the software to initially report all is OK but then show problems after a day or so as it gathers more accurate info, so leave it to run for a day or so before relying on the results.

There should be some free ones, no need to pay for it.

Flash and java are up to date.

I assume disable extensions means the same as disable add-ons. I ran FF in safe mode and got the same problem - go to mlive.com and it just freezes and then after a while it unfreezes and is working fine.

I installed HDD Heath. It shows health at 98% which I assume is good. I'll keep it there for a couple days and see if it shows anything different.

Have you tried using a different browser? Download Chrome here: https://www.google.com/intl/en/chrome/browser/

See if you have the same problem with the same websites. Chrome has flash built into it, so if it works, it may be a problem with flash for Firefox. Using Firefox, go here: http://get2.adobe.com/flashplayer/

Make sure you uncheck the McAfee Security Scan option... then download and install it. NOTE: You'll have to close firefox before installation for the installation to work properly.

If Chrome freezes too, then the problem may lie within Java... You said these are up to date, but they push updates frequently. The most current Java version as of the timestamp of this post is Java Version 7 Update 17. You can get it here: http://java.com/en/download/windows_xpi.jsp?locale=en

If chrome didn't freeze, but Firefox still does after installing the newest Flash and Java, then next step is to disable your add-ons.To view your add-ons in firefox, click the orange Firefox button in the top left of Firefox, then click Add-ons. Click Extensions from the left menu. Remove all extensions there. Next, go to Plugins in the left menu. You want to keep Adobe Acrobat, Java Deployment Toolkit, and Java Platform enabled. You may see a Shockwave Flash plugin-there as well, but disable it for now. (NOTE: Shockwave isn't too popular, but updating it may help as well: http://get.adobe.com/shockwave/)

Restart Firefox after you've disabled the Add-ons and test to make sure the sites work properly now.

Bingo!
My hard drive died just a short while after