I found a workaround. Gmail was not the only site with which I had this problem; it had something to do with all https connections (like https://www.gmail.com).

When FF tries to establish a SSL connections, it also tries to verify the validity of the cerfiticate provided by the webserver. Therefor it uses the OCSP protocol (Online Certificate Status Protocol).

I disabled the OCSP check (options -> advanced -> encryption -> validate).

After I disabled it, I could access again the https secured websites (like gmail, ogone, etc) using Firefox.

It's strange that this feature was activated - or malfunctioned - after the upgrade to FF7. In earlier versions of the browser (on the same computer) it was never a problem. I cannot verify anymore if OCSP was enabled in the previous versions.

Anyway, this workaround worked for me, but I'm not happy with it (I think that certificate validation is a good thing; it helps against spoofing).

Many thanks I tried exactly as you recommended. Unfortunately it made no difference. I looked a little further and noticed Google recognises it as a know problem. Many thanks Tony