Firefox in FC10, this is a weirdy

[Jim]

FC10, Firefox-3
If i type in URL  lxer.com or linuxtoday.com Firefox says it can't find 
server at http://www.lxer.com or www.linuxtoday.com .

I can go to yahoo.com, redhat.com, foxnews.com without any problems.

On my FC8, Firefox-2.0 Laptop on same network , if I type in lxer.com or 
linuxtoday.com Firefox-2.0 doesn't inject a www. in front of URL, and I 
can go to both URL's without any problems.

Firefox-3 on FC10 always puts a www. in front of URL.

And what makes this more weird is that I have installed on a FC8  x86_64 
box , Remi/FC8 Firefox/3.0 and it doesn't inject
http://www.lxer.com , it always comes up as http://lxer.com  and goes to 
website with no problems.
So it seems for lxer.com and linuxtoday.com if the www. is injected it 
can't find those two websites.
Even if I type in on the X86_64 box http://www.lxer.com, it eliminates 
the www. and gives a http://lxer.com and goes to the website

I'm perplexed.