can't logout from dashboard – version 3.1.3

I can’t logout from the dashboard (or anywhere else) in several of the installations I have, I couple work. I have tried different browsers, computers, disabling all pluging, and setting to the default themes.

the logout link is
https://foodfashionanddesign.com/wp-login.php?action=logout&_wpnonce=<number&gt;

I get the following error

The connection was reset
The connection to the server was reset while the page was loading.
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

Edited….
Clearing browser cookies worked on one site but not another.

regards…