Why won't my computer load my homepage on start-up, which is the sign-on page for "gmail", after up-grading to Firefox-6?

Question

Upgraded to Firefox6 a week ago when "suggested" by pop-up screen. Since then, computer will not open gmail using Mozilla but will access it through IE. I get the following message:-
* The connection has timed out
* The server at www.google.com is taking too long to respond.
* The site could be temporarily unavailable or too busy. Try again in a few moments.
* 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
What is the problem? Anything to do with "incompatibility with Microsoft and/or Google" - again?
I can access all my other regular sites through Mozilla.

Answer 1

Apple's Wireless Diagnostics may supply some additional helpful information.
To use it, hold an option key while you click your Mac's Wi-Fi icon, and choose Open Wireless Diagnostics...
The following authentication dialog will appear:
Authenticate with your Admin password, then click the Continue button in the following:
The network analysis and diagnostic tests will take several minutes to complete:
When it completes, if your wireless network is functioning properly the following will result:
If something is amiss, supposedly the results will be different and you will be presented with helpful information.
Assuming your connection is "working as expected" select Continue to summary and click Continue:
Ignore the pre-populated text field, which is provided as a place for you to type in additional information should Apple ask for it in the course of obtaining technical assistance from them. Apple has no way of knowing where your router is located in your home, and certainly doesn't know if you even have an upstairs bedroom closet.
Click Continue.
The next step will also take a few minutes:
When it finishes, you will be presented with a summary that may or may not be useful to you. Let me know if it is.
The WirelessDiagnostics-xxx.tar.gz file deposited on your Desktop can be dragged to the Trash, or you may wish to expand it and examine its contents. It's up to you.