I'm still getting a lot of the same messages on Firefox. Maybe it's just a gliche in my browser?

Server not found
Firefox can't find the server at finance.yahoo.com.

* Check the address for typing errors such as
ww.example.com instead of
www.example.com

* If you are unable to load any pages, check your computer's network
connection.

* If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.

Do you have problems when using other browsers? Have a look if there are any newdotnet/new.net plugins installed in firefox.

But maybe a reinstall/update of Firefox is in order.

On occassion, I'm getting the page cannot be found message in IE as well. I updated firefox 2 days ago, thinking as well that might be the problem.

Try uninstalling and reinstalling Firefox , maybe the previous version that you had before , or the latest.