Firefox refusing to load random sites

[Cyber Akuma]

Windows 2000
Pentium 3 1.13GHZ
128 megs SDRAM
GeForce3 TI200 64meg AGP

I dont know how this really happened, but firefox for some reason is refusing to load random sites. The sites are always the same one, but there seems to be nothing in common with the sites it will and wont load. Sites like www.aol.com and www.imageshack.us are two of the ones that wont load, when I try it looks like its loading the page but then just gives me a blank page. The sites load in IE fine. The page's source is blank too when I try to view it in Firefox. The only thing I can think of that could have had any influence on this is that I installed PeerGuardian2 recently, but its not running right now. A reboot didnt help.

[Cyber Akuma]

It looks like whatever this is, its associated with my profile. When I moved my profile folder to somewhere else and started firefox, all my settings were back to default but the sites could load again. When I moved the folder back they were blocked again. Somehow the stires got blocked in my user profile for Firefox. I dont know how or why, but more importantly I cant tell where they are exactly so I can unblock them.

[Cyber Akuma]

Well, I was slowly moving file by file on my configuration until I hit a file that disables those sites when its there but the sites load when the file isnt there.

The file was "prefs.js"

Since this was just an ASCII file with a bunch of lines of configuration, I looked through it and didnt see anything that could potentially be causing this problem. So I started with a new configuration file and slowly started copy/pasting the lines from the old one until I could duplicate the problem.

Turns out the line "user_pref("browser.cache.memory.enable", false);" was causing it, dosent really make sense to me but many sites dont load if that line is there, they load fine when its not, or rather, when its set to true.

[Cherokee]

Did you by chance disable memory cache with your user.js file?

This is from Firefox Tips & Tricks: (http://www.mozilla.org/support/firefox/tips)
Specify the memory cache usage

Normally, Firefox determines the memory cache usage dynamically based on the amount of available memory. To specify a specific amount of memory cache, add the following code to your user.js file:

// Specify the amount of memory cache:
// -1 = determine dynamically (default), 0 = none, n = memory capacity in kilobytes
user_pref("browser.cache.memory.capacity", 4096);

To disable the memory cache completely, add the following code:

// Disable memory cache:
user_pref("browser.cache.memory.enable", false);
The browser.cache.memory.capacity setting determines how the browser uses RAM for cache. I have a small HDD (20GB) with 384MB RAM, so I opted for the 4096 cache memory capacity.

You should also be diligent about keeping your Cache cleared. You can either do it in Tools | Options | Privacy | Cache,
or
with Firefox closed, open Windows Explorer and navigate to the random character file:
< path >Mozilla\Firefox\Profiles\xxxxxxxx.xxx
Delete the entire Cache folder