Usually caused by your firewall doing its job; not recognizing the new version of Firefos. Clear permissions for Firefox from the programs section of your firewall, let the firewall detect the new version, and give the proper permissions for Firefox to access the internet.
See: http://support.mozilla.com/en-US/kb/Cannot+connect+after+upgrading+Firefox

Went through all the steps uninstalled 3.0.10 downloaded 3.6.13, made sure it was in the list of allowed programs, same problem won't launch, un-installed it,reinstalled 3.0.10 launched immediately, I'm at a loss

The article and links to the Firewall applications tell you to remove Firefox from the Firewall programs list. You then start Firefox, let the Firewall re-detect the new version of Firefox and give the proper permissions.

Except in unusual circumstances, it is not necessary to un-install and re-install Firefox.

1. Which Firewall are you using?
   
2. Do you have more than one Firewall installed? You should not as this may decrease any protection offered by either Firewall.

I have windows vista firewall and I believe there is one in avast anti virus, I went through the steps again, windows did not detect firefox 3.6.13 and it does not start after install, I also have a pop-up blocker Stop-zilla don't know if that has anything to do with it, but the minute I go back to 3.0.10 everything works

You should have no problem if you are only using one Firewall and one AV/AS application.

If you click on the link

1. "Windows Firewall" in the article that I posted earlier , it will take you to another article
2. on the new page, if you click on "Windows Vista" in the Table of Contents
3. it takes you to this section of the article: http://support.mozilla.com/en-US/kb/Configuring%20Windows%20Firewall#w_windows-vista
   
4. Follow those step-by-step instructions for "Checking..." and "Configuring..." Windows Vista Firewall and your problem will most likely be resolved.

Note that nowhere in either of those articles is un-installing and re-installing Firefox mentioned.

didn" un=install anything went through step by step same thing does not launch. only way to get firefox to open is to intsll 3.0 after the other won't open- opens right up????