ARI broken after upgrading

Hi, We have just upgraded a system to v2.7.0 and installed all the latest module updates.

However the ARI panel is now broken-
We can log into the recordings webpage with the username and password.
However, if we click on any menu items we are logged out again straight away and sent back to the login page!

The http error log shows this:
PHP Notice: session_start() [function.session-start]: Server localhost (tcp 11211) failed with: Connection refused (111) in /var/www/html/recordings/includes/bootstrap.php on line 263, referer:

Can anyone help??