Gmail in Firefox 15
 

It is a bit strange that when I open Gmail in Firefox 15, It get refreshed again and again (About once or twice a minute).
How can I determine the source of this phenomenon?
It is 4 days that I have migrated to Slackware and haven't updated it yet. I don't remember seeing this event in Firefox 22.

I think this can be from a MITM attacker trying to get more data of Gmail HTTPS session.

time to upgrade firefox
the current is firefox 22

the FTP page
https://ftp.mozilla.org/pub/mozilla....leases/latest/

I have updated to Firefox 22 manually and still had the problem of reloading Gmail.
After that tried to update the whole of Slackware. It still had the problem by firefox 17.0.7
I tried to use Firefox 22 again. It has the problem too.
I think the problem is about opening one of Google's websites "apis.google.com"; It can not load it. Does not go further of "apis.google.com"

is "no-script" installed ?
if so is it set to block google

or did you remove the google cookies
and have checked " block all removed cookies "

if gmail can not set the cookies it will not work

No, I do not have any add-on installed.
Also I did not to try removing the google cookies. I think they haven't been removed. Because I have set the "Stay online" and when I start Firefox I just go to mail.google.com and it doesn't prompt for username/password.