Problem Solved
The solution in my case for this problem, on Fasthosts shared platform was solved by
WEBASSIST corrected the problem by editing the WA_SecurityAssist/helper_php.php file at line 4-6, ichange the code:
if (!isset($_SESSION)) {
session_start();
}
to:
//if (!isset($_SESSION)) {
@session_start();
//}
we have found that some servers aren't responding to the if (!isset($_SESSION)) { if statement to force php to find the session.
commenting the if statement and just using:
@session_start();
does the same thing more predictably.