WHMCS - some clients not able to login.  PHP Session Problem?

Some clients are having problems logging in to the clientarea. If the user goes to the clientarea.php and trys to log in with the right username and password the page just refreshes and the login form clears. No error no nothing.

This happens intermittenly to people across different browsers. Safari Mac seems to have a problem, firefox 8.0.1 Windows has had a problem, and IE 8 has had the problem. But even across browsers its inconsistent to believe its a browser problem.

I use a custom template, and i have tried going back to the default template from whmcs and it still happened.

Like i said it happens sometimes to different people. But its happening to many times that i need to fix it.

It is really weird ... for example.

I try to login as my client on Safari iMac... i can login fine.
I try to login as my client on Safari Macbook Pro ... i CANT login.  The login form just clears and nothing happens

both safaris are Version 5.1.2 (7534.52.7)

I see the login page very briefily go to a dologin.php page (in safari) but then just redirects to the cl
clientarea.php page.

ive tried chmod 1777 /var/lib/php/session

current permissions are
drwxrwxrwt 2 root apache 233472 Jan 15 08:36 session

Anybody have any ideas where to start?

Ive attached my phpinfo for sessions.