Firefox and os x 10.7.5

Good evening,

I am using macbook A1181 w/os x 10.7.5

Some time ago I started having problems w/Safari not working properly. It wouldn't allow me to open some sites on the internet and I couldn't get it fixed. I got so frustrated w/it that I switched to Firefox.

Everything was going well until last week. Once again, it won't open certain sites. I did a google search then clicked on the answer I wanted to read and Firefox brought up the site for a moment and then rerouted to a page saying it couldn't process the get request or there was a page error.

Do you know how I can fix this and if not, do you know what IP will let me just surf the web and open pages w/o having to allow them to track me? Why would it work for weeks and then stop working?

I don't want to be tracked so I have chosen that under security using exceptions to sites I visit.

Thanks again for your help,