BSU,
open NIS, the go to "personal firewall". You will see 2 boxes "turn off" and "configure". Click on "configure".
You will the get a choice of 5 pages. Open the one marked "programs"
You will then get a list of all the programs that NIS recognises.
Scroll down until you find firefox. Use your mouse, and left click on it. then move the cursor to the "internet access" column, and click again.
You can then change it to allow internet access.
Hope this works.