Can you try opening up Firefox in Safe Mode? Go to Start -> All Programs -> Mozilla Firefox -> Mozilla Firefox (Safe Mode). Safe Mode will temporarily disable your add-ons and custom settings, which will help to figure out if the problem is within Firefox or something else about your system or network.

It's also might be worth trying to connect to a different network to see if the problem is your router or connection.

I have mozilla open in firefox and it is not possible to get another connection. I am wireless and everyone close by is and they also have a secure network

Which security software (firewall) do you have?

Some can corrupt or change the HTTP response headers if not configured properly and change the content type to text/plain.

ESET Smart Security 4.0 I've had for 6mos now and it hasn't bothered firefox at all. It isn't a virus right?

It's possible, but it's really hard to say without seeing it first hand--I suspect the issue isn't with Firefox though. Another easy test I forgot to ask you to try: does this problem happen in any other browsers (Internet Explorer, Google Chrome, Safari, etc.)?

So far it is hasn't happened with IE. I only have the two browsers. I'm waiting for it to happen again so I an upload a picture of what it looks like in hopes that it will help find out what's wrong with firefox