I have the same problem on a fresh install of 3.6.3 on Windows Vista. Once I changed my home page from the Firefox/google start page to my iGoogle page, it would not load on the first try and displayed "The connection was reset. The connection to the server was reset while the page was loading." The page loaded properly when I pressed retry or the refresh icon. The same error message shows when I click on a link from an e-mail in Outlook. One thing that helped was I put https at the beginning of my homepage, instead of http, and it now loads on the first time.

I have the same problem with Firefox 3.6.3. for windows xp and linux ubuntu 8.10. It works normaly on firefox 3.5.9 an earlier.